  We have searched for second generation leptoquark (LQ) pairs in the
\mu\mu+jets channel using 94+-5 pb^{-1} of pbar-p collider data collected by
the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a
signal is observed. These results are combined with those from the \mu\nu+jets
and \nu\nu+jets channels to obtain 95% confidence level (C.L.) upper limits on
the LQ pair production cross section as a function of mass and $beta, the
branching fraction of a LQ decay into a charged lepton and a quark. Lower
limits of 200(180) GeV/c^2 for \beta=1(1/2) are set at the 95% C.L. on the mass
of scalar LQ. Mass limits are also set on vector leptoquarks as a function of
\beta.
