1
                                                       Filed by Monsanto Company
                           Pursuant to Rule 425 under the Securities Act of 1933
                                        and deemed filed pursuant to Rule 14a-12
                                          of the Securities Exchange Act of 1934

                                               Subject Company: Monsanto Company
                                                   Commission File No. 001-02516


         On January 27, 2000, Monsanto Company ("Monsanto"), a Delaware
corporation, and Pharmacia & Upjohn, Inc. ("P&U"), a Delaware corporation,
delivered the following letter to their employees:

Dear Colleagues,

         One of the most visible issues for any new company is the selection of
a corporate name and a logo. In choosing a name for our new, combined company,
we wanted to honor the past of both companies, but also to mark the creation of
something entirely new. After careful evaluation, we've come to the following
decisions:

         -    The new company will be named Pharmacia. We think it's a great
              name because it expresses our goal of creating a top-tier
              global pharmaceutical company. It also works well in many
              languages -- and, as it happens, we already own the name,
              which will save us lots of time and cost.

         -    The new logo and look for our corporate identity will come
              from Searle's graphics -- the familiar blue and the
              distinctive typeface. For a preview, visit the P&U Merger News
              intranet site.

         -    And, to express our new beginnings, we want to involve the
              creativity of all our people in crafting a new corporate
              "tagline" -- a phrase or sentence that will accompany the
              Pharmacia name and express our qualities and aspirations.

         -    The Monsanto name will live on in our global agriculture
              business.



   2





         Pharmacia will be our corporate or enterprise name. But underneath that
name, other names will continue to be used -- names like "Upjohn," "Searle" and
"DeKalb," for example. These areas of our business, among others, will continue
to leverage their value in the marketplace and maintain the important customer
relationships we've built over the years. And, just as importantly, these names
mean a lot to many of us, as they signify the hard work, proud histories and
future potential that we care deeply about.

         In the weeks ahead, we'll be working on the specifics of the graphic
design. More information about the tagline contest and about how we'll use the
new logo and brand names on business cards, letterheads, etc., will be
communicated in the coming weeks.

         The selection of the name for our new company is a meaningful first
step forward in our journey to create one of the most dynamic, fastest-growing
companies in our industry. We appreciate your continued focus on the business,
and your commitment to achieving the enormous business potential that lies
ahead.

Thanks, and best regards.

Bob Shapiro     Fred Hassan


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

Monsanto and Pharmacia & Upjohn will be filing a joint proxy statement/
prospectus and other relevant documents concerning the merger with the United
States Securities and Exchange Commission (the "SEC"). WE URGE INVESTORS TO READ
THE JOINT PROXY STATEMENT/PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS TO BE
FILED WITH THE SEC, BECAUSE THEY CONTAIN IMPORTANT INFORMATION. Investors will
be able to obtain the documents free of charge at the SEC's website,
www.sec.gov. In addition, documents filed with the SEC by Monsanto will be
available free of charge from the Secretary of Monsanto at 800 North Lindbergh
Blvd., St. Louis, Missouri 63167, Telephone (314) 694-1000. Documents filed with
the SEC by Pharmacia & Upjohn will be available free of charge from the
Corporate Secretary of Pharmacia &
   3

Upjohn, 100 Route 206 North, Peapack, NJ 07977, Telephone (888) 768-5501. READ
THE JOINT PROXY STATEMENT/PROSPECTUS CAREFULLY BEFORE MAKING A DECISION
CONCERNING THE MERGER.

Monsanto, its directors, executive officers and certain other members of
management and employees may be soliciting proxies from Monsanto stockholders
in favor of the merger. Information concerning the participants in the
solicitation is set forth in the Current Report on Form 8-K filed by Monsanto
with the SEC on January 25, 2000.