EXHIBIT 10.61

[Solexa, Inc. Letterhead]

April 21, 2005

ValueAct Capital
435 Pacific Avenue, 4th Floor
San Francisco, CA 94133
Attn: G. Mason Morfit

Re: Board Of Directors Representative

Dear Mason:

     This purpose of this letter is to confirm the understanding between Solexa,
Inc., a Delaware company (the “Company”)and ValueAct Capital Master Fund, L.P.
(“ValueAct”) in connection with the Company’s private placement of common stock
and warrants pursuant to that certain Securities Purchase Agreement, dated
April 21, 2005, by and between the Company and the individuals and entities
identified on the signature pages hereto (the “Purchase Agreement”).

     Effective and contingent upon of the First Closing (as defined in the
Purchase Agreement) and until ValueAct no longer owns at least 734,500 shares of
the Company’s common stock (as appropriately adjusted for any stock dividend,
stock split, reverse split, reclassification or the like), ValueAct shall have
the right to nominate one member of the Company’s Board of Directors, which
nominee shall initially be G. Mason Morfit.

     
Very truly yours,
   
 
   
Solexa, Inc.

   
/s/ John West
         
John West
   
Chief Executive Officer
   
 
   
Accepted and Agreed:
   
 
   
ValueAct Capital Master Fund, L.P.

   
/s/ George F. Hamel 
         
By its General Partner, VA Partners, LLC
   
George F. Hamel, Jr.
   
Managing Member