Search For The Decay D-0-]Mu(+)Mu(-)

We have searched for the decay D-0 --> mu(+)mu(-) among 1.25 x 10(5) mu(+)mu(-) pairs produced by 350 GeV/c pi(-) particles interacting in copper and tungsten targets. Using a high-resolution silicon-microstrip detector followed by a large-acceptance magnetic spectrometer and a muon filter we are able to discriminate between prompt and non-prompt muons and to measure dimuon masses. No candidate compatible with a D-0 --> mu(+)mu(-) decay has been found, allowing us to set an upper limit on the branching fraction B(D-0 --> mu(+)mu(-)) of 7.6 x 10(-6) at the 90% confidence level.