Exhibit 10.4

                         trilogy capital partners, inc.


                              Letter of Engagement
                           Applied DNA Sciences, Inc.
                                  June 20, 2005


The following  sets forth the agreement  for the  engagement of Trilogy  Capital
Partners,  Inc.  ("Trilogy")  by  Applied  DNA  Sciences,  Inc.  ("APDN"  or the
"Company"):


Term and            Twelve months, commencing as of the date set forth above
Termination         (the "Initial Term"), and terminable thereafter by either
                    party upon 30 days' prior written notice.

Objective           The development and implementation of a proactive marketing
                    program to increase the awareness of APDN and generate a
                    significant increase in liquidity and market capitalization.
                    In addition, upon request, Trilogy will advise APDN in
                    business development and strategic advisory services.

The Program         Trilogy will structure and implement a marketing program
                    designed to create extensive financial market and investor
                    awareness for APDN to drive long-term shareholder support.
                    The core drivers of the program will be to create
                    institutional and retail buying in the Company's stock
                    through a proactive sales and marketing program emphasizing
                    technology-driven communications, coupled with 1-to-1
                    selling and leveraging APDN's image to attract additional
                    long term investors and to create additional opportunities
                    in M&A and Business Development. As share price is affected
                    by various factors, Trilogy can give no assurance that the
                    marketing program will result in an increase in APDN's stock
                    price.

                    Trilogy understands that during any period in which the
                    Company is in "registration" for a public offering of
                    securities under the Securities Act of 1933, and during the


                    distribution of such securities, the Company's investor
                    relations and marketing efforts will be severely limited.
                    However, it will be the responsibility of the Company (with
                    the advice of its securities counsel) to determine what
                    investor relations and financial marketing efforts are
                    permissible and non-permissible during such periods, and
                    Trilogy will follow the direction of the Company and its
                    securities counsel.

Responsibilities    In addition to marketing and financial public relations,
                    Trilogy will assume the responsibilities of an in-house
                    Investor Relations Officer for APDN on a full turnkey basis,
                    including the generation of corporate and shareholder
                    communications, retail and institutional investor contact
                    and media. Trilogy will work in conjunction with the
                    Company's management, securities counsel, investment bankers
                    and auditors and under supervision of management. The
                    content is as follows:

                    o Campaign Development and Execution
                    o Press Announcements: drafting, approval and distribution
                    o Database Development and Management
                    o Image Analysis: recommendations and implementation
                    o Messaging: institutional and retail
                    o Online presentations: drafting and production
                    responsibilities
                    o Website Overhaul - installation and maintenance of auto IR
                      program
                    o Email messaging: targets: Retail and Institutional/Other
                      databases
                    o Media including Interactives and PowerPoints
                    o Direct Mail: shareholder, media, APDN relationship
                      universe
                    o Public Relations
                    o Capital Conferences

                    Trilogy will not publish or publicly release any press
                    release or other document ("IR Documents") regarding the
                    Company that has not been approved in writing by the
                    Company. The Company assumes responsibility for the accuracy
                    and completeness of all IR Documents and the compliance of
                    such Documents with applicable laws, rules and regulations.
                    The Company agrees that Trilogy has no obligation or duty to
                    verify the accuracy or completeness of the IR Documents.

Fees                $12,500 per month, with first payment due on execution.
                    Wiring information is set forth below.


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Equity              APDN has concurrently herewith issued to Trilogy 7,500,000
Compensation        Warrants. Each Warrant represents the right to purchase one
                    share of Common Stock for $0.55 per share at any time
                    through the third year following issuance. The Company
                    agrees to file a Registration Statement with the Securities
                    and Exchange Commission registering the shares underlying
                    the Warrants no later than the earlier to occur of: (i) 15
                    days following the effectiveness of the Company's current
                    registration statement on Form SB-2 (File No. 333-122848)
                    and (ii) September 19, 2005.

Marketing           To support the financial marketing program, APDN
Budget              acknowledges that it will incur certain third party
                    marketing costs. Trilogy will not incur these costs on
                    behalf of the Company except with the approval of the
                    Company or pursuant to a budget approved by the Company
                    (which budget shall not be more than $200,000 unless
                    approved by an officer of the Company). The Company shall
                    have no obligation to reimburse Trilogy for any third party
                    marketing cost that exceeds the approved budget or is
                    otherwise not approved by the Company. The Company
                    understands that prompt payment of these costs is vital to
                    the on-going investor relations program, and therefore shall
                    pay these costs promptly upon invoice, to Trilogy (to enable
                    Trilogy to promptly reimburse these third parties). The
                    Company shall indemnify and hold Trilogy harmless from any
                    losses, claims, costs, expenses, liabilities and damages
                    from failure to timely pay these third party marketing
                    costs.

Indemnification     The Company agrees to provide the indemnification set forth
                    in "Exhibit A" attached hereto.

Corporate           The obligations of Trilogy are solely corporate obligations,
Obligations         and no officer, director, employee, agent, shareholder or
                    controlling person of Trilogy shall be subject to any
                    personal liability whatsoever to any person, nor will any
                    such claim be asserted by or on behalf of any other party to
                    this Agreement.

Additional          If Trilogy is called upon to render services directly or
Services            indirectly relating to the subject matter of this Agreement,
                    beyond the services contemplated above (including, but not
                    limited to, production of documents, answering
                    interrogatories, giving depositions, giving expert or other
                    testimony, whether by agreement, subpoena or otherwise), the
                    Company shall pay to Trilogy a reasonable hourly rates for

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                    the persons involved for the time expended in rendering such
                    services, including, but not limited to, time for meetings,
                    conferences, preparation and travel, and all related costs
                    and expenses and the reasonable legal fees and expenses of
                    Trilogy's counsel.

Survival of         The Sections entitled "Indemnification" (including "Exhibit
Certain             A"), "Corporate Obligations" and "Additional Services" shall
Provisions          survive any termination of this Agreement and Trilogy's
                    engagement pursuant to this Agreement. In addition, such
                    termination shall not terminate Trilogy's right to
                    compensation accrued through the date of termination and for
                    reimbursement of expenses (including third party marketing
                    costs). Any purported termination of this Agreement by the
                    Company prior to the end of the Initial Term, or any
                    termination by Trilogy as a result of non-payment or other
                    material breach by the Company (including the failure to pay
                    third-party marketing costs), shall not terminate Trilogy's
                    right to the fees through the entire Initial Term (as
                    Trilogy's time and commitment are expected to be greater in
                    the first part of its engagement).

Services/Costs      The compensation paid to Trilogy under this Agreement will
                    cover all costs for Trilogy personnel. Travel and
                    entertainment costs for Trilogy personnel, in addition to
                    certain third-party costs, will be borne by the Company.
                    Trilogy will provide reasonable documentation to support
                    reimbursement claims. Trilogy will not incur any particular
                    reimbursable cost of $500 or more without the written
                    approval from the Company. These reimbursable costs are not
                    third-party marketing costs under "Marketing Budget."

Attorneys' Fees     If any action or proceeding is brought to enforce or
                    interpret any provision of this Agreement, the prevailing
                    party shall be entitled to recover as an element of its
                    costs, and not its damages, reasonable attorneys' fees to be
                    fixed by the court.

Governing Law       California, without giving
                    effect to the principles of conflicts of law thereof.

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                         [Signatures on following page.]


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Agreed and Accepted:

Applied DNA Sciences, Inc.                   Trilogy Capital Partners, Inc.


By   /s/ PETER BROCKLESBY                    By   /s/ PAUL KARON
     --------------------                         --------------
         Peter Brocklesby                             Paul Karon
         President                                    President



By   /s/ KARIN KLEMM
     ---------------
         Karin Klemm
         COO / CFO