  We have searched for the flavor-changing neutral current decay b -> s mu+ mu-
in p pbar collisions at sqrt(s) = 1.8 TeV with the DO detector at Fermilab. We
determine the 90% confidence level limit for the branching fraction to be B(b
-> X_s mu+ mu-) < 3.2 x 10^{-4}. We argue that this limit is more stringent
than the best published limit on this decay rate.
