  We present experimental results on b-hadron mass measurements and b-meson
oscillations based on integrated luminosity of 250 to 450 pb-1 of
proton-antiproton collisions at c.m. energy = 1.98 TeV by the CDF and D0
collaborations at the Tevatron. The masses of b-hadrons have been measured
precisely by the CDF collaboration in decays containing a J/psi . A blind
search of the decay mode Bc to J/psi pi resulted in a peak of 18.9 +/- 5.4
candidates at a mass value of 6287.0 +/- 4.5 +/- 1.1 MeV/c2. A new limit has
been set to the decay B_d,s to mu+ mu-. Both the CDF and D0 collaborations are
in the position to put a limit on the frequency of the Bs oscillations. D0
reports Delta m_s > 5.0 ps-1.
