
<PAGE>
 
                                                                   EXHIBIT 99.3
                                 ASHLAND INC.
 
                             OFFER TO EXCHANGE ITS
                         6 5/8% SENIOR NOTES DUE 2008,
         WHICH HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
                    FOR UP TO $150,000,000 PRINCIPAL AMOUNT
                              OF ITS OUTSTANDING
                         6 5/8% SENIOR NOTES DUE 2008
 
To: Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees:
 
  Ashland Inc. (the "Company") is offering to exchange (the "Exchange Offer"),
upon and subject to the terms and conditions set forth in the Prospectus,
dated      , 1998 (the "Prospectus"), and the enclosed Letter of Transmittal
(the "Letter of Transmittal"), its registered 6 5/8% Senior Notes Due 2008
(the "New Notes") for up to $150,000,000 aggregate principal amount of its
outstanding 6 5/8% Senior Notes Due 2008 (the "Old Notes"). The Exchange Offer
is being made in order to satisfy certain obligations of the Company contained
in the Registration Rights Agreement dated as of February 17, 1998, between
the Company and the Initial Purchasers.
 
  We are requesting that you contact your clients for whom you hold Old Notes
regarding the Exchange Offer. For your information and for forwarding to your
clients for whom you hold Old Notes registered in your name or in the name of
your nominee, or who hold Old Notes registered in their own names, we are
enclosing the following documents:
 
    1. Prospectus dated          , 1998;
 
    2. The Letter of Transmittal for your use and for the information of your
  clients;
 
    3. A Notice of Guaranteed Delivery to be used to accept the Exchange
       Offer if certificates for Old Notes are not immediately available or
       time will not permit all required documents to reach the Exchange
       Agent prior to the Expiration Date (as defined below) or if the
       procedure for book-entry transfer cannot be completed on a timely
       basis;
 
    4. A form of letter which may be sent to your clients for whose account
       you hold Old Notes registered in your name or the name of your
       nominee, with space provided for obtaining such clients' instructions
       with regard to the Exchange Offer;
 
    5. Guidelines for Certification of Taxpayer Identification Number on
  Substitute Form W-9; and
 
    6. Return envelopes addressed to Citibank, N.A., the Exchange Agent for
  the Old Notes.
 
  YOUR PROMPT ACTION IS REQUESTED. THE EXCHANGE OFFER WILL EXPIRE AT 5:00
P.M., NEW YORK CITY TIME, ON          , 1998 (THE "EXPIRATION DATE") (20
BUSINESS DAYS FOLLOWING THE COMMENCEMENT OF THE EXCHANGE OFFER), UNLESS
EXTENDED BY THE COMPANY. THE OLD NOTES TENDERED PURSUANT TO THE EXCHANGE OFFER
MAY BE WITHDRAWN AT ANY TIME BEFORE 5:00 P.M, NEW YORK CITY TIME, ON THE
EXPIRATION DATE.
 
  To participate in the Exchange Offer, a duly executed and properly completed
Letter of Transmittal (or facsimile thereof), with any required signature
guarantees and any other required documents, should be sent to the Exchange
Agent and certificates representing the Old Notes should be delivered to the
Exchange Agent, all in accordance with the instructions set forth in the
Letter of Transmittal and the Prospectus.
 
  If holders of Old Notes wish to tender, but it is impracticable for them to
forward their certificates for Old Notes prior to the expiration of the
Exchange Offer or to comply with the book-entry transfer procedures on a
timely basis, a tender may be effected by following the guaranteed delivery
procedures described in the Prospectus under "The Exchange Offer--Guaranteed
Delivery Procedures."
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  Any inquiries you may have with respect to the Exchange Offer, or requests
for additional copies of the enclosed materials should be directed to the
Exchange Agent for the Old Notes, at its address and telephone number set
forth on the front of the Letter of Transmittal.
 
                                          Very truly yours,
 
                                          Ashland Inc.
 
 
   NOTHING HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU OR ANY
 OTHER PERSON AS AN AGENT OF THE COMPANY OR THE EXCHANGE AGENT, OR AUTHORIZE
 YOU OR ANY OTHER PERSON TO USE ANY DOCUMENT OR MAKE ANY STATEMENTS ON BEHALF
 OF EITHER OF THEM WITH RESPECT TO THE EXCHANGE OFFER, EXCEPT FOR STATEMENTS
 EXPRESSLY MADE IN THE PROSPECTUS OR THE LETTER TO TRANSMITTAL.
 
 
Enclosures
