Omega(B) and Omega(0) from MACHOs and Local Group dynamics

We obtain restrictions on the universal baryon fraction, f(B) equivalent to Omega(B)/Omega(0), by assuming that the observed microlensing events towar d the Large Magellanic Cloud are due to baryonic MACHOs in the halo of the Galaxy and by extracting a bound to the total mass of the Milky Way from th e motion of tracer galaxies in the Local Group. We find a lower bound f(B), > 0.29(-0.15)(+0.18). Consistency with the predictions of primordial nucle osynthesis leads to the further constraint on the total mass density, Omega (0) less than or similar to 0.2.