Exhibit 10.6

July 28, 2014

Montaur Capital Partners LLC
Englewood, NJ
Attn: Luc Maasdorp

Gentlemen:

This letter (“Agreement”) is to confirm our mutual understanding with respect to
the terms and conditions under which Montaur Capital Partners LLC (“Consultant”)
agrees to provide Navidea Biopharmaceuticals, Inc. ( “Navidea”) with Consulting
Services during the period from July 1, 2014 until the termination of this
Agreement as provided below (the “Consulting Period”).

As used herein, the term “Consulting Services” means the services of
Consultant’s principal, Michael M. Goldberg, M. D. (“Dr. Goldberg”) as interim
chief executive officer of Navidea, and that this agreement is for the personal
services of Dr. Goldberg.

In exchange for performing the Consulting Services, regardless of the amount of
time devoted by Consultant or Dr. Goldberg to the performance thereof, Navidea
agrees to pay Consultant a flat monthly fee of $15,000, payable in arrears. The
parties acknowledge that no compensation will be paid by Navidea to Consultant
or to Dr. Goldberg for Dr. Goldberg’s services as interim chief executive
officer, and that the monthly fee payable to Consultant under this Agreement is
intended only to compensate Consultant for additional costs and resources
Consultant will be required to incur or redirect due to the diversion of Dr.
Goldberg from the management and other services he provides to Consultant
occasioned by his service as Navidea’s interim chief executive officer.

During the Consulting Period, either through the performance of Consulting
Services or otherwise, Consultant may acquire proprietary and confidential
information (herein “Information”) with respect to the business and research
activities of Navidea. Consultant agrees to keep confidential such Information
and not to divulge any such Information to others. Specifically, Consultant
agrees that it will not directly or indirectly, publish or disclose to others,
except with the written consent of Navidea, any Information, data or methods of
manufacture received or obtained from Navidea, nor use such Information in any
way, commercially or otherwise, except in performing the Consulting Services.
This obligation of confidentiality and non-use shall continue until three (3)
years after the termination of this Agreement, but shall not apply to
Information which (i) becomes a matter of public knowledge through no fault of
Consultant; (ii) is rightfully received by Consultant from a third party without
restriction on disclosure; (iii) is independently developed by Consultant
without the use of Information; or (iv) is rightfully in Consultant’s possession
prior to its disclosure to Consultant by Navidea.

Consultant hereby irrevocably transfer and assign to Navidea without further
compensation, any and all of its right, title and interest in and to all
designs, ideas, discoveries, inventions, products, computer programs, source
code, procedures, improvements, documents, information and materials made,

--------------------------------------------------------------------------------

Montaur Capital Partners LLC
July 28, 2014
Page 2 of 2

conceived or developed by Consultant alone or with others, which result from or
relate to the Consulting Services (“Work Product”), including, but not limited
to, all copyrightable works and copyrights, patent rights, trade secrets and
trademarks, any right to claim authorship of Work Product, or any right to
object to any distortion or other modification of Work Product by Navidea.
Notwithstanding this assignment and transfer, if any Work Product incorporates
or relies upon works developed by Consultant prior to the effective date of this
Agreement, Consultant shall continue to retain ownership of thereof, but
Consultant hereby licenses Navidea to use, or have third parties use on
Navidea’s behalf, such preexisting works as is reasonably required to fully
exploit the Consulting Services performed hereunder. Consultant agrees, during
and for one year following the term of the Agreement to: (i) disclose promptly
in writing to Navidea all Work Product; and (ii) to sign and provide any and all
documents and render any assistance that is reasonably necessary for Navidea to
obtain any patent, copyright, trademark or other protection for Work Product. In
case any invention is described in a patent application or is disclosed to third
parties by Consultant within one (1) year after the Consulting Services have
been completed, it shall be presumed that the invention was conceived or made
during the period in which the Consulting Services were rendered, and the
invention will be assigned to Navidea as set forth in this Agreement, provided
that the invention results from or relates to the Consulting Services. If the
invention was made by Consultant prior to any association with Navidea or was
made without the Information or resources of Navidea, then Consultant need not
assign the invention to the Company as set forth herein.

At the expiration of this Agreement, Consultant agrees to promptly deliver to
Navidea all documents, notes, or other papers supplied to it by Navidea in
connection with the Consulting Services, which were in Consultant’s possession
and under its control during the time Consultant provided the Consulting
Services to Navidea. Consultant agrees that it will not make or retain or give
away any copies of such documents.

Either party may terminate this Agreement with ten (10) business days’ prior
written notice to the other. Early termination of this Agreement by Navidea
shall not relieve Navidea of any liability for payment of consulting fees that
accrued prior to the date of termination of the Agreement, nor relieve
Consultant of any obligations with respect to the confidentiality and non-use of
Information, the transfer of rights in any Work Product, or the return to
Navidea of any documents, notes or other papers.

It is understood and agreed that the status of Consultant and Dr. Goldberg shall
be that of an independent contractor and not that of an employee of Navidea, and
neither will be entitled to any of the benefits available to employees of
Navidea. It is further understood and agreed that no representations have been
made to Consultant or Dr. Goldberg by Navidea that performance of the Consulting
Services described herein will lead to an offer of permanent employment with
Navidea.

This Agreement shall be construed and governed by the laws of the State of Ohio
and adjudicated within the exclusive jurisdiction of the courts having
jurisdiction over Franklin County, Ohio.

If the foregoing terms and conditions meet with your understanding and approval,
please show your acceptance and agreement by executing this letter in duplicate
at the place indicated below and returning one of the executed duplicates to us,
whereupon this letter shall constitute the agreement between Consultant and
Navidea with respect to the Consulting Services.

--------------------------------------------------------------------------------

Montaur Capital Partners LLC
July 28, 2014
Page 3 of 3

Very truly yours,

Navidea Biopharmaceuticals, Inc.

By: /s/ Brent L. Larson                    
Brent L. Larson
Executive Vice President and CFO

Accepted and agreed to:

Montaur Capital Partners LLC

By: /s/ Luc Maasdorp                    
Luc Maasdorp, Associate