```

                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM N-Q

                   QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS
    OF REGISTERED MANAGEMENT INVESTMENT COMPANY

  Investment Company Act file number 811-05099

                         Pioneer Money Market Trust
               (Exact name of registrant as specified in charter)

                       60 State Street, Boston, MA 02109
              (Address of principal executive offices) (ZIP code)

            Terrence J. Cullen, Pioneer Investment Management, Inc.,
                       60 State Street, Boston, MA 02109
                    (Name and address of agent for service)

Registrant's telephone number, including area code:  (617) 742-7825

Date of fiscal year end:  December 31

Date of reporting period:  March 31, 2017

Form N-Q is to be used by management investment companies, other than small
business investment companies registered on Form N-5 (239.24 and 274.5 of this
chapter), to file reports with the Commission, not later than 60 days after
close of the first and third fiscal quarters, pursuant to Rule 30b1-5 under
the Investment Company Act of 1940 (17 CFR 270.30b1-5).  The Commission may
use the information provided on Form N-Q in its regulatory, disclosure review,
inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-Q,
and the Commission will make this information public. A registrant is not
required to respond to the collection of information contained in Form N-Q
unless the Form displays a currently valid Office of Management and Budget
("OMB") control number. Please direct comments concerning the accuracy of the
information collection burden estimate and any suggestions for reducing the
burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW,
Washington, DC 20549-0609.  The OMB has reviewed this collection of information
under the clearance requirements of 44 U.S.C. ss. 3507.

<PAGE>
ITEM 1. Schedule of Investments.

File the schedules as of the close of the reporting period as set forth in
ss. 210.12-12  12-14 of Regulation S-X [17 CFR 210.12-12  12-14]. The
schedules need not be audited.
```

```

```

|   |   |                                                                                             |
|--------|--------|--------------------------------------------------------------------------------------------------|
|   |   |                                                                                             |
|   |   | Pioneer U.S. Government                                                                          |
|   |   | Money Market Fund                                                                                |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   | NQ | March 31, 2017                                                                              |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   | Ticker Symbols:                                                                                  |
|   |   | Class A              PMTXX |
|   |   | Class Y              PRYXX |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |
|   |   |                                                                                             |

|   | Principal  | FloatingRate (a) |                                                                                                                                                                                                                                                                                                                 |   |                                                          |
|--------|------------|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|---------------------------------------------------------------|
|   | Amount ($) | (unaudited)      |                                                                                                                                                                                                                                                                                                                 |   | Value                                                         |
|   |       |             | U.S. GOVERNMENT AND AGENCYOBLIGATIONS - 80.5%                                                                                                                                                                                                                                                                        |   |                                                          |
|   | 300,000    |             | Fannie Mae Discount Notes, 4/3/17 (b)                                                                                                                                                                                                                                                                                |   | $       300,000            |
|   | 200,000    |             | Fannie Mae Discount Notes, 4/7/17 (b)                                                                                                                                                                                                                                                                                |   | 199,984                                                       |
|   | 1,000,000  |             | Fannie Mae Discount Notes, 4/19/17 (b)                                                                                                                                                                                                                                                                               |   | 999,769                                                       |
|   | 300,000    | 1.03             | Federal Farm Credit Banks, Floating Rate Note, 4/28/17                                                                                                                                                                                                                                                               |   | 300,000                                                       |
|   | 1,500,000  | 0.88             | Federal Farm Credit Banks, Floating Rate Note, 5/8/17                                                                                                                                                                                                                                                                |   | 1,499,890                                                     |
|   | 2,000,000  | 1.04             | Federal Farm Credit Banks, Floating Rate Note, 5/9/18                                                                                                                                                                                                                                                                |   | 2,007,817                                                     |
|   | 400,000    | 0.97             | Federal Farm Credit Banks, Floating Rate Note, 7/6/18                                                                                                                                                                                                                                                                |   | 401,250                                                       |
|   | 1,500,000  |             | Federal Farm Credit Discount Notes, 4/26/17 (b)                                                                                                                                                                                                                                                                      |   | 1,499,281                                                     |
|   | 3,200,000  |             | Federal Home Loan Bank Discount Notes,4/5/17 (b)                                                                                                                                                                                                                                                                     |   | 3,199,879                                                     |
|   | 1,000,000  |             | Federal Home Loan Bank Discount Notes, 4/10/17 (b)                                                                                                                                                                                                                                                                   |   | 999,881                                                       |
|   | 400,000    |             | Federal Home Loan Bank Discount Notes, 4/13/17 (b)                                                                                                                                                                                                                                                                   |   | 399,919                                                       |
|   | 501,000    |             | Federal Home Loan Bank Discount Notes, 4/19/17 (b)                                                                                                                                                                                                                                                                   |   | 500,822                                                       |
|   | 1,739,000  |             | Federal Home Loan Bank Discount Notes, 4/21/17 (b)                                                                                                                                                                                                                                                                   |   | 1,738,339                                                     |
|   | 250,000    |             | Federal Home Loan Bank Discount Notes, 4/24/17 (b)                                                                                                                                                                                                                                                                   |   | 249,883                                                       |
|   | 900,000    |             | Federal Home Loan Bank Discount Notes, 4/27/17 (b)                                                                                                                                                                                                                                                                   |   | 899,538                                                       |
|   | 3,130,000  |             | Federal Home Loan Bank Discount Notes, 4/28/17 (b)                                                                                                                                                                                                                                                                   |   | 3,128,322                                                     |
|   | 100,000    |             | Federal Home Loan Bank Discount Notes,5/5/17 (b)                                                                                                                                                                                                                                                                     |   | 99,929                                                        |
|   | 300,000    |             | Federal Home Loan Banks, 0.875%, 3/1/18                                                                                                                                                                                                                                                                              |   | 299,798                                                       |
|   | 500,000    | 1.03             | Federal Home Loan Banks, Floating Rate Note, 6/22/17                                                                                                                                                                                                                                                                 |   | 500,000                                                       |
|   | 1,000,000  | 1.00             | Federal Home Loan Banks, Floating Rate Note, 7/27/17                                                                                                                                                                                                                                                                 |   | 999,975                                                       |
|   | 1,500,000  | 0.92             | Federal Home Loan Banks, Floating Rate Note, 8/15/17                                                                                                                                                                                                                                                                 |   | 1,500,000                                                     |
|   | 5,000,000  | 1.06             | Federal Home Loan Banks, Floating Rate Note, 11/2/17                                                                                                                                                                                                                                                                 |   | 5,002,052                                                     |
|   | 1,500,000  | 0.99             | Federal Home Loan Banks, Floating Rate Note, 12/1/17                                                                                                                                                                                                                                                                 |   | 1,500,128                                                     |
|   | 1,500,000  | 0.90             | Federal Home Loan Banks, Floating Rate Note, 12/7/17                                                                                                                                                                                                                                                                 |   | 1,500,334                                                     |
|   | 2,600,000  | 0.93             | Federal Home Loan Banks, Floating Rate Note, 2/5/18                                                                                                                                                                                                                                                                  |   | 2,605,034                                                     |
|   | 1,737,000  |             | Federal Home Loan Mortgage Corp., 1.25%, 5/12/17                                                                                                                                                                                                                                                                     |   | 1,737,566                                                     |
|   | 3,120,000  | 0.98             | Federal Home Loan Mortgage Corp., Floating Rate Note, 4/20/17                                                                                                                                                                                                                                                        |   | 3,120,210                                                     |
|   | 3,000,000  | 1.11             | Federal Home Loan Mortgage Corp., Floating Rate Note, 7/21/17                                                                                                                                                                                                                                                        |   | 3,000,292                                                     |
|   | 4,410,000  | 0.92             | Federal Home Loan Mortgage Corp., Floating Rate Note, 11/13/17                                                                                                                                                                                                                                                       |   | 4,413,534                                                     |
|   | 1,358,000  |             | Federal National Mortgage Association, 1.125%, 4/27/17                                                                                                                                                                                                                                                               |   | 1,358,125                                                     |
|   | 300,000    |             | Federal National Mortgage Association, 1.0%, 9/20/17                                                                                                                                                                                                                                                                 |   | 300,082                                                       |
|   | 460,000    |             | Federal National Mortgage Association, 0.875%, 10/26/17                                                                                                                                                                                                                                                              |   | 460,307                                                       |
|   | 3,880,000  | 1.00             | Federal National Mortgage Association, Floating Rate Note, 7/20/17                                                                                                                                                                                                                                                   |   | 3,882,078                                                     |
|   | 420,000    | 0.84             | Federal National Mortgage Association, Floating Rate Note, 10/5/17                                                                                                                                                                                                                                                   |   | 420,034                                                       |
|   | 3,000,000  |             | Freddie Mac Discount Notes, 4/26/17 (b)                                                                                                                                                                                                                                                                              |   | 2,998,582                                                     |
|   | 24,000,000 |             | U.S. Treasury Bills, 4/6/17 (b)                                                                                                                                                                                                                                                                                      |   | 23,999,105                                                    |
|   | 34,585,000 |             | U.S. Treasury Bills, 4/13/17 (b)                                                                                                                                                                                                                                                                                     |   | 34,579,400                                                    |
|   | 27,295,000 |             | U.S. Treasury Bills, 4/20/17 (b)                                                                                                                                                                                                                                                                                     |   | 27,285,694                                                    |
|   | 13,075,000 |             | U.S. Treasury Bills, 4/27/17 (b)                                                                                                                                                                                                                                                                                     |   | 13,068,639                                                    |
|   | 490,000    |             | U.S. Treasury Bills, 5/11/17 (b)                                                                                                                                                                                                                                                                                     |   | 489,692                                                       |
|   | 1,075,000  |             | U.S. Treasury Bills, 6/1/17 (b)                                                                                                                                                                                                                                                                                      |   | 1,073,795                                                     |
|   | 770,000    |             | U.S. Treasury Bills, 6/8/17 (b)                                                                                                                                                                                                                                                                                      |   | 769,012                                                       |
|   | 665,000    |             | U.S. Treasury Bills, 7/20/17 (b)                                                                                                                                                                                                                                                                                     |   | 663,921                                                       |
|   | 3,000,000  |             | U.S. Treasury Bills, 8/17/17 (b)                                                                                                                                                                                                                                                                                     |   | 2,993,512                                                     |
|   | 615,000    |             | U.S. Treasury Bills, 8/31/17 (b)                                                                                                                                                                                                                                                                                     |   | 612,940                                                       |
|   | 3,000,000  |             | U.S. Treasury Bills, 9/14/17 (b)                                                                                                                                                                                                                                                                                     |   | 2,992,014                                                     |
|   | 3,000,000  |             | U.S. Treasury Bills, 10/12/17 (b)                                                                                                                                                                                                                                                                                    |   | 2,989,832                                                     |
|   | Principal  | FloatingRate (a) |                                                                                                                                                                                                                                                                                                                 |   |                                                          |
|   | Amount ($) | (unaudited)      |                                                                                                                                                                                                                                                                                                                 |   | Value                                                         |
|   |       |             | U.S. GOVERNMENT AND AGENCYOBLIGATIONS - (continued)                                                                                                                                                                                                                                                                  |   |                                                          |
|   | 300,000    |             | U.S. Treasury Bills, 11/9/17 (b)                                                                                                                                                                                                                                                                                     |   | $       298,616            |
|   | 635,000    |             | U.S. Treasury Bills, 12/7/17 (b)                                                                                                                                                                                                                                                                                     |   | 631,310                                                       |
|   | 300,000    |             | U.S. Treasury Bills, 3/1/18 (b)                                                                                                                                                                                                                                                                                      |   | 297,399                                                       |
|   | 15,545,000 | 0.86             | U.S. Treasury Note, Floating Rate Note, 4/30/17                                                                                                                                                                                                                                                                      |   | 15,545,088                                                    |
|   | 15,615,000 | 0.86             | U.S. Treasury Note, Floating Rate Note, 7/31/17                                                                                                                                                                                                                                                                      |   | 15,618,266                                                    |
|   | 13,940,000 | 0.95             | U.S. Treasury Note, Floating Rate Note, 10/31/17                                                                                                                                                                                                                                                                     |   | 13,950,630                                                    |
|   | 14,485,000 | 1.05             | U.S. Treasury Note, Floating Rate Note, 1/31/18                                                                                                                                                                                                                                                                      |   | 14,511,829                                                    |
|   | 10,715,000 | 0.97             | U.S. Treasury Note, Floating Rate Note, 4/30/18                                                                                                                                                                                                                                                                      |   | 10,728,647                                                    |
|   | 3,500,000  | 0.96             | U.S. Treasury Note, Floating Rate Note, 7/31/18                                                                                                                                                                                                                                                                      |   | 3,501,145                                                     |
|   | 790,000    |             | U.S. Treasury Notes, 0.875%, 5/15/17                                                                                                                                                                                                                                                                                 |   | 790,330                                                       |
|   | 300,000    |             | U.S. Treasury Notes, 4.5%, 5/15/17                                                                                                                                                                                                                                                                                   |   | 301,360                                                       |
|   | 625,000    |             | U.S. Treasury Notes, 0.875%, 8/15/17                                                                                                                                                                                                                                                                                 |   | 625,504                                                       |
|   | 620,000    |             | U.S. Treasury Notes, 1.875%, 9/30/17                                                                                                                                                                                                                                                                                 |   | 623,456                                                       |
|   | 785,000    |             | U.S. Treasury Notes, 0.625%, 11/30/17                                                                                                                                                                                                                                                                                |   | 783,965                                                       |
|   | 465,000    |             | U.S. Treasury Notes, 2.25%, 11/30/17                                                                                                                                                                                                                                                                                 |   | 469,350                                                       |
|   | 785,000    |             | U.S. Treasury Notes, 1.0%, 12/15/17                                                                                                                                                                                                                                                                                  |   | 785,859                                                       |
|   |       |             | TOTAL U.S. GOVERNMENT ANDAGENCY OBLIGATIONS                                                                                                                                                                                                                                                                          |   |                                                          |
|   |       |             | (Cost  $245,002,944)                                                                                                                                                                                                                                                                                       |   | $245,002,944                                                  |
|   |       |             | TEMPORARY CASH INVESTMENTS - 19.5%                                                                                                                                                                                                                                                                                   |   |                                                          |
|   |       |             | REPURCHASE AGREEMENTS - 19.5%                                                                                                                                                                                                                                                                                        |   |                                                          |
|   | 15,130,000 |             | $15,130,000 RBC Capital Markets LLC, 0.79%, dated 3/31/17 plus accrued interest on4/3/17 collateralized by the following:$637,709 Freddie Mac, 2.646% - 3.364%, 6/1/37 - 5/1/45,$14,794,892 Federal National Mortgage Association, 2.357% - 4.232%, 11/1/27 - 3/1/47                                                 |   | $15,130,000                                                   |
|   | 15,130,000 |             | $15,130,000 ScotiaBank, 0.81%,dated 3/31/17 plus accrued interest on4/3/17 collateralized by the following:$5,189,843 Freddie Mac, 2.5% - 3.5%,11/1/29 - 11/1/46,$10,000,272 Federal National Mortgage Association, 1.764% - 4.5%, 7/1/27 - 11/1/47,$243,526 Government National Mortgage Association, 2.0%, 9/20/44 |   | 15,130,000                                                    |
|   | 13,755,000 |             | $13,755,000 TD Securities USA LLC, 0.80%, dated 3/31/17 plus accrued interest on4/3/17 collateralized by the following:$14,030,100 Federal National Mortgage Association, 4.0%, 2/1/47                                                                                                                               |   | 13,755,000                                                    |
|   | 15,130,000 |             | $15,130,000 TD Securities USA LLC, 0.81%,dated 3/31/17 plus accrued interest on4/3/17 collateralized by the following:$15,432,601 Federal National Mortgage Association, 4.0%, 2/1/47                                                                                                                                |   | 15,130,000                                                    |
|   |       |             |                                                                                                                                                                                                                                                                                                                 |   | $59,145,000                                                   |
|   |       |             | TOTAL TEMPORARY CASH INVESTMENTS                                                                                                                                                                                                                                                                                     |   |                                                          |
|   |       |             | (Cost  $59,145,000)                                                                                                                                                                                                                                                                                        |   | $59,145,000                                                   |
|   |       |             | TOTAL INVESTMENT IN SECURITIES - 100.0%                                                                                                                                                                                                                                                                              |   |                                                          |
|   |       |             | (Cost  $304,147,944) (c)                                                                                                                                                                                                                                                                                   |   | $304,147,944                                                  |
|   |       |             | OTHER ASSETS & LIABILITIES - 0.0%†                                                                                                                                                                                                                                                                         |   | $         36,381 |
|   |       |             | NET ASSETS - 100.0%                                                                                                                                                                                                                                                                                                  |   | $304,184,325                                                  |
|   |

| † | Amount rounds to less than 0.1%.                                                        |
|---------|-----------------------------------------------------------------------------------------|
|    |                                                                                    |
| (a)     | Debt obligation with a variable interest rate. Rate shown is rate at end of period.     |
|    |                                                                                    |
| (b)     | Security issued with a zero coupon. Income is recognized through accretion of discount. |
|    |                                                                                    |
| (c)     | At March 31, 2017, cost for federal income tax purposes was $304,147,944.               |

| Various inputs are used in determining the value of the Fund's investments. These inputs are summarized in the three broad levels below.                         |   |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|
|                                                                                                                                                             |   |
| Level 1 - quoted prices in active markets for identical securities.                                                                                              |   |
| Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risks, etc.). |   |
| Level 3 - significant unobservable inputs (including the Fund's own assumptions in determining fair value of investments).                                       |   |
|                                                                                                                                                             |   |
| The following is a summary of the inputs used as of March 31, 2017, in valuing the Fund's investments:                                                           |   |
|                                                                                                                                                             |   |
|                                                                                                                                                             |   | Level 1 |   |   | Level 2 |   |   | Level 3 |   |   | Total |   |
|                                                                                                                                                             |   |
| U.S. Government andAgency Obligations                                                                                                                            |   | $ | – |   |   | $ | 245,002,944 |   |   | $ | – |   |   | $ | 245,002,944 |   |
| Repurchase Agreements                                                                                                                                            |   |   | – |   |   |   |  59,145,000 |   |   |   | – |   |   |   |  59,145,000 |   |
| Total                                                                                                                                                            |   | $ | – |   |   | $ | 304,147,944 |   |   | $ | – |   |   | $ | 304,147,944 |   |
|                                                                                                                                                             |   |