<PAGE>
                                                                  EXHIBIT 4.13.1


            THIS SECURITY IS A GLOBAL SECURITY AND IS REGISTERED IN THE NAME OF
A DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE
OR IN PART FOR A SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE
OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH
DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES SET FORTH
IN OR PURSUANT TO THE INDENTURE.

            UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE
OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC" OR THE
"DEPOSITARY"), TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE, OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF
CEDE & CO., OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO., OR TO SUCH OTHER
ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER
PLEDGE, OR OTHER USE THEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS
WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.


                              BANKNORTH GROUP, INC.
                        3.75% SENIOR NOTE DUE MAY 1, 2008

Registered: No. 1                                             CUSIP: 06646R AB 3
                                                                    $150,000,000

            BANKNORTH GROUP, INC., a corporation duly organized and existing
under the laws of the State of Maine (herein called the "Company", which term
includes any successor Person under the Indenture hereinafter referred to), for
value received, hereby promises to pay to Cede & Co., or registered assigns, the
principal sum of ONE HUNDRED FIFTY MILLION DOLLARS ($150,000,000) on May 1,
2008, and to pay interest thereon from April 30, 2003, or from the most recent
Interest Payment Date to which interest has been paid or duly provided for,
semi-annually on May 1 and November 1 of each year, commencing November 1, 2003,
at the rate of 3.75% per annum, until the principal hereof is paid or made
available for payment. Interest on this Security shall be calculated on the
basis of a 360-day year consisting of twelve 30-day months. The interest so
payable, and punctually paid or duly provided for, on any Interest Payment date
will, as provided in such Indenture, be paid to the Person in whose name this
Security (or one or more Predecessor Securities) is registered at the close of
business on the Regular Record Date for such interest, which shall be the April
15 or October 15 (whether or not a Business Day), as the case may be, next
preceding such Interest Payment Date. Any such interest not so punctually paid
or duly provided for will forthwith cease to be payable to the Person who was
the Holder of this Security on the relevant Regular Record Date by virtue of
having been such Holder and may either be



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paid to the Person in whose name this Security (or one or more Predecessor
Securities) is registered at the close of business on a Special Record Date for
the payment of such Defaulted Interest to be fixed by the Company, notice
whereof shall be given to Holders of the Securities of this series, not less
than 10 days prior to such Special Record Date, or be paid at any time in any
other lawful manner not inconsistent with the requirements of any securities
exchange on which the Securities of this series may be listed, and upon such
notice as may be required by such exchange, all as more fully provided in said
Indenture.

            Payment of the principal of and interest on this Security will be
made at the office or agency of the Company maintained for that purpose in the
Borough of Manhattan, The City of New York, in such coin or currency of the
United States of America as at the time of payment is legal tender for payment
of public and private debts; provided, however, that at the option of the
Company payment of interest may be made by check mailed to the address of the
person entitled thereto as such address shall appear in the Security Register or
by wire transfer to an account designated by such person pursuant to an
arrangement that is satisfactory to the Trustee and the Company; and provided,
further, that, notwithstanding the foregoing, so long as this Security is a
global Security registered in the name of a depositary or its nominee, payments
of the principal of and interest on this Security shall be made by wire transfer
of immediately available funds.

            Reference is hereby made to the further provisions of this Security
set forth on the reverse hereof; which further provisions shall for all purposes
have the same effect as if set forth at this place.

            Unless the certificate of authentication hereon has been executed by
the Trustee referred to on the reverse hereto by manual signature, this Security
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

                [Remainder of this page intentionally left blank]




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<PAGE>


            IN WITNESS WHEREOF, the Company has caused this instrument to be
duly executed under its corporate seal.


Dated:  April 30, 2003                    BANKNORTH GROUP, INC.

[Seal]                                    By:
                                          --------------------------------------
                                          Name:  William J. Ryan
                                          Title: Chairman, President and Chief
Attest:                                          Executive Officer


-----------------------------------
Name:  Carol Mitchell
Title: Executive Vice President and
       General Counsel



            TRUSTEE'S CERTIFICATE OF AUTHENTICATION

            This is one of the Securities of the series designated herein
referred to in the within-mentioned Indenture.

                                          THE BANK OF NEW YORK



                                          By:
                                             -----------------------------------
                                                     Authorized Signatory




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<PAGE>



                               REVERSE OF SECURITY

            This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities") issued and to be issued in one or more
series under an Indenture, dated as of April 30, 2003 (herein called the
"Indenture", which term shall have the meaning assigned to it in such
instrument), between the Company and The Bank of New York, a New York banking
corporation, as Trustee (herein called the "Trustee" which term includes any
successor trustee under the Indenture). Reference is hereby made to the
Indenture for a statement of the respective rights, limitations of rights,
duties and immunities thereunder of the Company, the Trustee and the Holder of
the Securities and the terms upon which the Securities are, and are to be,
authenticated and delivered. This Security is one of the series designated on
the face hereof, initially limited in aggregate principal amount to
$150,000,000, but subject to the Company's right to "reopen" the series and
issue additional Securities of such series from time to time.

            The Securities of this series are not subject to redemption at the
option of the Company prior to the Stated Maturity of the principal thereof.

            If an Event of Default with respect to Securities of this series
shall occur and be continuing, the principal of and accrued and unpaid interest
on the Securities of this series may be declared due and payable in the manner
and with the effect provided in the Indenture.

            The Indenture permits, with certain exceptions therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of Securities of each series issued under
the Indenture at any time by the Company and the Trustee with the consent of the
Holders of not less than a majority in aggregate principal amount of the
Securities at the time Outstanding of each series affected thereby. The
Indenture also contains provisions permitting the Holders of specified
percentages in principal amount of the securities of each series at the time
Outstanding, on behalf of the Holders of all Securities of such series, to waive
compliance by the Company with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by the Holder of this Security shall be conclusive and binding upon such
Holder and upon all future Holders of this Security and of any Security issued
upon the registration of transfer hereof or in exchange or in lieu hereof,
whether or not notation of such consent or waiver is made upon this Security.

            As provided in and subject to the provisions of the Indenture,
Holders of Securities of this series shall not have the right to institute any
proceeding with respect to the Indenture or for the appointment of a receiver or
trustee or for any other remedy thereunder, unless such Holders shall have
previously given the Trustee written notice of a continuing Event of Default
with respect to the Securities of this series, the Holders of not less than 25%
in principal amount of the Securities of this series at the time Outstanding
shall have made written request to the Trustee to institute proceedings in
respect of such Event of Default as Trustee and offered the Trustee indemnity
reasonably



                                       4
<PAGE>

satisfactory to it, and the Trustee shall not have received from the Holders of
a majority in principal amount of Securities of this series at the time
Outstanding a direction inconsistent with such request, and shall have failed to
institute any such proceeding for 60 days after receipt of such notice, request
and offer of indemnity. The foregoing shall not apply to any suit instituted by
Holders of Securities of this series for the enforcement of any payment of
principal hereof or any interest hereon on or after the respective due dates
expressed herein.

            No reference herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the
Company, which is absolute and unconditional, to pay the principal of and
interest on this Security at the times, place and rate, and in the coin or
currency prescribed herein and in the Indenture.

            As provided in the Indenture and subject to certain limitations
therein set forth, the transfer of this Security is registrable in the Security
Register, upon surrender of this Security for registration of transfer at the
office or agency of the Company in any place where the principal of and any
interest on this Security are payable, duly endorsed by, or accompanied by a
written instrument of transfer in form satisfactory to the Company and the
Security Registrar duly executed by the Holder hereof or his attorney duly
authorized in writing, and thereupon one or more new Securities of this series
and of like terms and tenor, of authorized denominations and for the same
aggregate principal amount, will be issued to the designated transferee or
transferees.

            The Securities of this series are issuable only in registered form
without coupons in denominations of $1,000 and any integral multiple thereof. As
provided in the Indenture and subject to certain limitations therein and herein
set forth, Securities of this series are exchangeable for a like aggregate
principal amount of Securities of this series and of like terms and tenor of a
different authorized denomination, as requested by the Holder surrendering the
same.

            The global Securities of this series will be exchangeable for
definitive certificated Securities of this series if (i) the depositary for such
global Securities notifies the Company that it is unwilling or unable to
continue as depositary for such global Securities or at any time such depositary
ceases to be a clearing agency registered as such under the Securities Exchange
Act of 1934, as amended (or any successor thereto), if so required by applicable
law or regulation, and the Company shall not have appointed a successor
depositary for such global Securities within 90 days of such notification or of
the Company becoming aware of the depositary's ceasing to be so registered, as
the case may be, (ii) the Company, in its sole discretion determines that the
global Securities of this series shall be exchangeable for definitive
certificated Securities of this series and executes and delivers to the Trustee
a Company Order to the effect that such global Securities shall be so
exchangeable, or (iii) an Event of Default has occurred and is continuing with
respect to the Securities of this series. If any global Security of this series
is exchangeable pursuant to the preceding sentence, it shall be exchanged,
without charge, for definitive certificated Securities of this series issued in
authorized denominations and registered in such names as the depositary shall
direct, and the Company will deliver to the Trustee definitive certificated
Securities of this series,



                                       5
<PAGE>

executed by the Company, in order to effect such exchange. Subject to the
foregoing, a global Security of this series is not exchangeable, except for a
Security of this series to be registered in the name of such depositary or its
nominee or in the name of a successor to the depositary or a nominee of such
successor depositary.

            No service charge shall be made for any registration of transfer or
exchange of this Security, but the Company may require payment of a sum
sufficient to cover any tax or other governmental charge payable in connection
therewith, other than in certain cases provided in the Indenture.

            Prior to due presentment of this Security for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name this Security is registered as the owner
hereof for all purposes, whether or not this Security be overdue, and neither
the Company, the Trustee nor any such agent shall be affected by notice to the
contrary.

            The Indenture and this Security shall be governed by and construed
in accordance with the laws of the State of New York.

            All terms used in this Security which are defined in the Indenture
shall have the meaning assigned to them in the Indenture.




                                       6
<PAGE>



                                  ABBREVIATIONS

            The Following abbreviations, when used in the inscription on the
fact of this instrument, shall be construed as though they were written out in
full according to applicable laws or regulations:

TEN COM -   as tenants in common

TEN ENT -   as tenants by the entireties

JT TEN -    as joint tenants with right of survivorship and not as tenants in
            common

       UNIF GIFT MIN ACT ......................Custodian .......................
                                 (Cust)                          (Minor)

       under Uniform Gifts to Minors Act .......................................
                                                       (State)

            Additional abbreviations may also be used though not in the above
list.

            FOR VALUE RECEIVED the undersigned hereby sells, assigns and
transfer unto

        [PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE]

        [NAME AND ADDRESS OF ASSIGNEE, INCLUDING ZIP CODE, MUST BE PRINTED OR
        TYPEWRITTEN]

the within Security, and all rights thereunder, hereby irrevocably constituting
and appointing, such person attorney to transfer said Security on the books of
the Company, with full power of substitution in the premises.

Dated:
       ------------------------

            NOTICE: The signature to this assignment must correspond with the
name as it appears upon the face of the within Security in every particular,
without alteration or enlargement or any change whatever.



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