  We present the results of a search for the flavor changing neutral current
decay B_s^0->mu^+mu^- using 6.1 fb^-1 of ppbar collisions at sqrt(s) = 1.96 TeV
collected by the D0 experiment at the Fermilab Tevatron Collider. The observed
number of B_s^0 candidates is consistent with background expectations. The
resulting upper limit on the branching fraction is BR(B_s^0->mu^+mu^-) < 5.1 x
10^-8 at the 95% C.L. This limit is a factor of 2.4 better than that of the
previous D0 analysis and the best limit to date.
