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                                                                     EXHIBIT 4.1

                            U.S. PLASTIC LUMBER CORP.

                           CERTIFICATE OF AMENDMENT TO
                 THE CERTIFICATE OF DESIGNATION OF PREFERENCES,
                           RIGHTS, AND LIMITATIONS OF
                      SERIES D PREFERRED STOCK, 15% COUPON

         The undersigned, being the Vice President and the Secretary of U.S.
Plastic Lumber Corp., a Nevada corporation (the "Corporation"), in accordance
with the provisions of Section 78.1955 of Nevada Revised Statutes, as amended
("NRS"), do hereby certify:

         That, pursuant to the authority conferred upon the Board of Directors
of the Corporation (the "Board of Directors") by the Restated Articles of
Incorporation and pursuant to the provisions of NRS, said Board of Directors, on
September 8, 2000, duly adopted resolutions providing for the issuance of one
series of Seven Hundred and Fifteen Thousand (715,000) shares of Series D
Preferred Stock, 15% Coupon, stated value $3.50 and par value $.001 per share.

         That, (i) pursuant to the authority vested in the Board of Directors by
the Corporation's Restated Articles of Incorporation and Amended and Restated
Bylaws, the Board of Directors, acting by unanimous written consent dated as of
June 1, 2001, adopted a resolution to amend and restate the Certificate of
Designation of Preferences, Rights, and Limitations of Series D Preferred Stock,
15% Coupon (the "Certificate of Designation"), filed with the Office of the
Nevada Secretary of State on October 12, 2000, and (ii) in accordance with
Section 78.1955(3) of NRS and the applicable terms of the Restated Articles of
Incorporation of the Corporation, the holders of Series D Preferred Stock, 15%
Coupon, acting by unanimous written consent dated as of June 1, 2001, approved
such resolution to amend and restate the Certificate of Designation, all as
contemplated by Section 78.1955(3) of NRS, which resolution is as follows:

         RESOLVED, that the Corporation be, and it hereby is, authorized to
amend and restate the Certificate of Designation as follows:

                  1.       Designation. The designation of the series of stock
         created by this resolution shall be "Series D Preferred Stock, 15%
         Coupon" (the "Series D Preferred Stock") and the number of shares
         constituting the Series D Preferred Stock shall be One Million One
         Hundred Eighty-Seven Thousand Two Hundred and Eighty-Five (1,187,285).
         Each share of the Series D Preferred Stock shall have a stated value
         equal to $3.50 (the "Stated Value"). The Preferred Stock does not
         entitle the holder thereof to voting rights, except as may be required
         by law. Each share of Preferred Stock is convertible: (i) at the option
         of the holder, subject to certain rights of the Corporation, into
         common stock of the Corporation (the "Common Stock") at the rate of 1
         share of the Common Stock for each share of the Series D Preferred
         Stock, and (ii) mandatorily converted into the Common Stock on March 1,
         2002. The Corporation shall use its best efforts to register the
         underlying Common Stock on or before June 30, 2001.

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                  2.       Interest. The 15% Coupon ("interest") will be paid on
         the Preferred Stock quarterly in arrears on a cash basis commencing on
         date of funding, at a rate of 15% per annum, and prorated if conversion
         occurs prior to the end of any quarter. The first quarterly interest
         payment will be made on March 31, 2001 and then quarterly thereafter.
         Interest payments shall cease effective with the date of conversion
         into the Common Stock, whether voluntary or mandatory conversion.

                  3.       Liquidation Preference. In the event of any
         liquidation, dissolution or winding up of the affairs of the
         Corporation, whether voluntary or otherwise, after payment of provision
         for payment of the debts and other liabilities of the Corporation, the
         holders of the Series D Preferred Stock shall be entitled to receive,
         before the holders of any of the Common Stock or other classes of
         Preferred Stock of the Corporation ranking junior thereto, out of the
         remaining net assets of the Corporation, the Stated Value of the Series
         D Preferred Stock. After such payment shall have been made in full to
         the holders of the outstanding Series D Preferred Stock, or funds or
         assets necessary for such payment shall have been set aside in trust
         for the account of the holders of the outstanding Series D Preferred
         Stock, so as to be and continue to be available therefor, the holders
         of the outstanding Series D Preferred Stock shall be entitled to no
         further participation in such distribution of the assets of the
         Corporation.

                  In the event that, after payment or provision for payment of
         the debts and other liabilities of the Corporation and preferences or
         other rights granted to the holders of the Series D Preferred Stock,
         the remaining net assets of the Corporation are not sufficient to pay
         the liquidation preference of the holders of the Series D Preferred
         Stock, then no such distribution shall be made on account of any shares
         of any other class or series of capital stock of the Corporation
         ranking, on a parity with the shares of the Series D Preferred Stock
         upon such liquidation unless proportionate distributive amounts shall
         be paid on account of each share of the Series D Preferred Stock,
         ratably, in proportion to the full distributable amounts for which
         holders of all such parity shares, including other shares of the Series
         D Preferred Stock, are respectively entitled upon such liquidation.

                  4.       Conversion of Preferred Stock into Common Stock. Each
         share of the Series D Preferred Stock shall be: (i) convertible at the
         option of the holder thereof pursuant to paragraph 4(a) below and (ii)
         automatically and mandatorily converted upon the occurrence of the
         event described pursuant to paragraph 4(b) below. In either event, any
         such shares of the Series D Preferred Stock shall be converted into
         fully paid and nonassessable shares of the Common Stock.

                           (a)      Voluntary Conversion. Subsequent to March
                  31, 2001, the holder of any share(s) of the Series D Preferred
                  Stock shall have the right to convert any such share(s) into
                  fully paid and nonassessable shares of the Common Stock of the
                  Corporation in accordance with the Conversion Ratio (defined
                  below); as the same may be adjusted from time to time. In
                  order to convert the shares of the Series D Preferred Stock
                  into the Common Stock, the holder shall surrender at the
                  office of any transfer agent for the Corporation, a
                  certificate(s) therefore, duly endorsed to the Corporation or
                  in blank, and give written notice to the



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                  Corporation at said office that he or she elects to convert
                  such shares. Shares of the Series D Preferred Stock shall be
                  deemed to have been converted immediately prior to the close
                  of business on the date of surrender of such shares for
                  conversion and the person(s) entitled to receive shares of the
                  Common Stock issuable upon such conversion shall be treated,
                  for all purposes, as the record holder(s) of such shares of
                  the Common Stock at such time. As promptly as practicable
                  after the conversion, the Corporation shall issue and deliver
                  at said offices a certificate(s) for the number of full shares
                  of the Common Stock issuable upon such conversion, to the
                  person(s) entitled to receive the same. The Corporation shall
                  issue the certificate(s) for the Common Stock in the name(s)
                  so designated with such legends affixed or restrictions
                  imposed as required by federal, state or jurisdictional
                  securities laws as determined by legal counsel for the
                  Corporation; provided that the Corporation is not advised by
                  its counsel that the issuance of such certificate(s) would be
                  in violation of federal, state or jurisdictional securities
                  law.

                           (b)      Mandatory Conversion. Subject to any other
                  provision of this paragraph 4, each holder of record of any
                  share(s) of the Series D Preferred Stock shall convert such
                  holder's share(s) of the Series D Preferred Stock, in whole or
                  in part, in accordance with the Conversion Ratio (defined
                  below), subject to the adjustments set forth below, on March
                  1, 2002. The Corporation shall also have a right to force
                  mandatory conversion of the Series D Preferred Stock into the
                  Common Stock prior to March 1, 2002, at any time after the
                  Corporation registers the underlying Common Stock and such
                  registration statement is declared effective by the Securities
                  and Exchange Commission; provided, however, that (i) the stock
                  of the Corporation is trading at an average closing price of
                  $3.50 per share for the 20 trading days immediately preceding
                  the date of the Corporation's notice to the holder, and (ii)
                  the Corporation provides notice to the holder equal to a
                  minimum of 10 days and maximum of 30 days notice. Such notice
                  shall specify the time and place thereof and shall be given by
                  mail to each holder of record of shares of the Series D
                  Preferred Stock at the address last shown on the records of
                  the Corporation for such holder or given by such holder to the
                  Corporation for the purpose of notice or, if no such address
                  appears or is given, at the place where the principal
                  executive office of the holder is located. Any notice which
                  was mailed in the manner herein provided shall be conclusively
                  presumed to have been duly given whether or not the holder
                  received the notice.

                           (c)      Additional Provisions Applicable to All
                  Conversions. Any conversion of the Series D Preferred Stock
                  into the Common Stock pursuant to this paragraph 4 shall be
                  subject to following additional terms and provisions:

                                    (1)      All shares of the Series D
                           Preferred Stock shall be convertible (or, as the case
                           may be, automatically converted) into the Common
                           Stock at the rate of 1 share of the Common Stock for
                           each share of the Series D Preferred Stock (the
                           "Conversion Ratio"), subject to the adjustments set
                           forth in this paragraph 4(c) below.

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                                    (2)      Subject to compliance with all
                           applicable securities laws, as soon as practicable
                           after the surrender for conversion of any
                           certificate(s) representing Series D Preferred Stock
                           (in the case of an elective conversion) or after the
                           Mandatory Conversion (as provided for in paragraph
                           4(b)), the Corporation shall deliver or cause to be
                           delivered at the principal office of the Corporation
                           (or such other place as may be designated by the
                           Corporation), to each holder of the Series D
                           Preferred Stock, certificates representing, the
                           shares of the Common Stock issuable upon such
                           conversion, issued in such name or names as such
                           holder may direct. Except as otherwise provided
                           herein, shares of the Series D Preferred Stock shall
                           be deemed to have been converted in the case of an
                           elective conversion pursuant to paragraph 4(a), as of
                           the close of business on the date of the surrender
                           for conversion of the certificates representing
                           Series D Preferred Stock, or in the case of an
                           automatic conversion pursuant to paragraph 4(b), as
                           of the close of business on the Automatic Conversion
                           Date, and in either case the rights of such holders
                           of the Series D Preferred Stock shall cease, and the
                           person(s) in whose name(s) the certificates for such
                           shares are to be issued shall be treated for all
                           purposes as having become the record holder(s) of
                           such Common Stock, at such time, or if such day shall
                           not constitute a business day, then the close of
                           business on the next succeeding business day.

                                    (3)      The Corporation shall not be
                           required to issue any fractions of shares of the
                           Common Stock upon conversions of any shares of the
                           Series D Preferred Stock. If more than one share of
                           the Series D Preferred Stock shall be surrendered for
                           conversion at one time by the same holder, the number
                           of full shares of the Common Stock which shall be
                           issuable upon conversion of such Series D Preferred
                           Stock shall be computed on the basis of the aggregate
                           number of shares of the Series D Preferred Stock so
                           surrendered. If any interest in a fractional share
                           would otherwise be deliverable upon the conversion of
                           any shares of the Series D Preferred Stock, the
                           Corporation shall not be required to issue any such
                           fractional share interest or make a cash payment for
                           any such fractional interest.

                                    (4)      In the event that the Corporation
                           shall at any time subdivide or combine in a greater
                           or lesser number of shares the outstanding shares of
                           the Common Stock, the number of shares of the Common
                           Stock issuable upon conversion of any shares of
                           Series D Preferred Stock prior to the occurrence of
                           such event shall be proportionately increased or
                           decreased as the case may be, effective following the
                           close of business on the record date for
                           determination of the Common Stock entitled to such
                           sub-division or combination in either case at the
                           close of business on the record date when such
                           subdivision or combination was adopted by the
                           Corporation.

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                                    (5)      In the event that the Corporation
                           shall be consolidated with or merged into any other
                           corporation, provision shall be made as part of the
                           terms of such consolidation or merger so that any
                           holder of the Series D Preferred Stock may thereafter
                           receive in lieu of the Common Stock otherwise
                           issuable to him or her upon conversion of his or her
                           shares of Series D Preferred Stock, but only in
                           accordance with the Conversion Ratio stated in this
                           paragraph 4, the same kind and amount of securities
                           as may be distributable upon such consolidation or
                           merger with respect to the Common Stock.

                                    (6)      In the event that the Corporation
                           shall at any time pay to the holders of the Common
                           Stock a dividend in the Common Stock, the number of
                           shares of the Common Stock of the Corporation
                           issuable upon any conversion of the Series D
                           Preferred Stock shall be proportionately increased,
                           effective following the close of business on the
                           record date for determination of the holders of the
                           Common Stock entitled to such dividend.

                                    (7)      Such adjustments shall be made
                           successively if more than one event listed in
                           paragraphs 4(c)(4) or 5 shall occur; provided,
                           however, that no adjustment need be made by the
                           Corporation until such adjustments cumulatively
                           aggregate at least five percent (5%) of the then
                           current Conversion Ratio.

                                    (8)      No adjustment of the Conversion
                           Ratio shall be made by any event or occurrence other
                           than those enumerated in this paragraph 4(c).

                                    (9)      The issuance of certificates for
                           shares of the Common Stock upon conversion of any
                           shares of the Series D Preferred Stock shall be made
                           without charge for any tax in respect of such
                           issuance. However, if any certificate is to be issued
                           in a name other than that of the holder of record as
                           the Series D Preferred Stock so converted, the person
                           or persons requesting, the issuance thereof shall pay
                           to the Corporation the amount of any tax which may be
                           payable in respect of any transfer involved in such
                           issuance, or shall establish to the satisfaction of
                           the Corporation that such tax has been paid or is not
                           due and payable.

                  5.       Voting Rights. Except as otherwise required by law or
         as otherwise specifically provided herein, the holders of the Series D
         Preferred Stock shall not be entitled to vote at any meeting of the
         stockholders for the election of directors or for any other purpose or
         otherwise to participate in any action taken by the Corporation of the
         stockholders thereof.

                  6.       Ranking. As long as any shares of the Series D
         Preferred Stock remain outstanding, the Corporation shall not, without
         obtaining the prior written consent of the

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         holders of at least a majority in number of the shares of the Series D
         Preferred Stock then outstanding, create, authorize or issue any other
         class or series of capital stock of the Corporation, the terms of which
         provide that such class or series shall rank prior to the Series D
         Preferred Stock in respect to rights upon dissolution, liquidation or
         winding up of the Corporation; provided, however, the Corporation may
         at any time create, authorize or issue, without the consent of any of
         the holders of the Series D Preferred Stock, other classes or series of
         capital stock which rank junior to, or on parity with, the Series D
         Preferred Stock in respect to dissolution, liquidation or winding up of
         the Corporation.

                  7.       Amendments. This Certificate of Designation may be
         amended by (i) the affirmative vote of not less than sixty percent
         (60%) of the holders of the Series D Preferred Stock currently
         outstanding, at the time such amendment is proposed, or (ii) the
         affirmative vote of not less than two-thirds of the directors of the
         Corporation then holding office and entitled to vote on such amendment.

         IN WITNESS WHEREOF, the Corporation has caused this Certificate of
Amendment to the Certificate of Designation to be signed by Michael D. Schmidt,
its Vice President of Finance, and Bruce Rosetto, its Secretary, as of this 13th
day of June, 2001.

                                            U.S. PLASTIC LUMBER CORP.

                                            By:    /s/ Michael D. Schmidt
                                               ---------------------------------
                                            Name:  Michael D. Schmidt
                                            Title: Vice President of Finance


                                            By:    /s/ Bruce C. Rosetto
                                               ---------------------------------
                                            Name:  Bruce C. Rosetto
                                            Title: Secretary



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STATE OF FLORIDA           )
                           )
COUNTY OF PALM BEACH       )

                  Before me, the undersigned authority, personally appeared
Michael D. Schmidt and Bruce Rosetto, who I personally know or have otherwise
identified themselves to my satisfaction to be the persons described in and who
executed the foregoing instrument as the Vice President of Finance and the
Secretary, respectively, of U.S. Plastic Lumber Corp., a Nevada corporation, and
did acknowledge before me that they executed the same as such officers of said
corporation by due and regular corporate authority.

                  WITNESS, my hand and official seal in the aforesaid County and
State this 13th day of June, 2001.



                                                     /s/ Grace F. Solomon
                                                     ---------------------------
                                                     Notary Public
                                                     State of Florida