Exhibit 4b

                      SECOND AMENDMENT TO RIGHTS AGREEMENT

THIS SECOND  AMENDMENT TO RIGHTS  AGREEMENT dated as of January 28, 2000, by and
between Atrion Corporation,  a Delaware corporation (the "Company") and American
Stock Transfer & Trust Company (the "Rights Agent").

                                    RECITALS

A. The Company and the Rights Agent are parties to that certain Rights Agreement
dated as of February 1, 1990, as heretofore amended (the "Rights Agreement").

B. The Rights  Agreement  provides  that the  Rights  (as  defined in the Rights
Agreement)  may be  exercised  after the  Distribution  Date (as  defined in the
Rights  Agreement) at or prior to the earliest to occur of the close of business
on  February  1, 2000 which is defined  as the "Final  Expiration  Date" and two
other events set forth therein.

D. The Board of Directors of the Company desires to extend the Final  Expiration
Date until February 1, 2005.

NOW THEREFORE,  in consideration of the mutual agreements set forth herein,  and
in  accordance  with  Section 27 of the Rights  Agreement,  the  Company and the
Rights Agent hereby agree as follows:

1.  Clause (i) of  Section  7(a) of the Rights  Agreement  is hereby  amended by
deleting  said clause in its entirety  and  substituting  the  following in lieu
thereof:

  "(i) the close of business on February 1, 2005 (the "Final Expiration Date"),"

2. Except as amended hereby, the Rights Agreement shall remain in full force and
effect.

IN WITNESS WHEREOF,  the parties have executed this Second Amendment on the date
first written above.

                                         ATRION CORPORATION

                                             -----------------------------
                                         By: /s/ Emile A. Battat
                                           Its Chairman and President

                                         AMERICAN STOCK TRANSFER & TRUST
                                         COMPANY

                                             -----------------------------
                                         By: /s/ Herbert J. Lemmer
                                           Its Vice President