We report the LEP results on B 0 -B 0 oscillations, together with a review of the analysis strategies. Many measurements of the B d 0 oscillation frequency have been performed giving an average, Δm d =0.486+/-0.015ps - 1 . Lower limits on Δm s are presented, giving a LEP-combined limit, Δm s >11.8ps - 1 , with an expected exclusion limit of 14.5ps - 1 . When combined with SLD and CDF, a tantalising 2.2σ effect at about 17ps - 1 is observed, having a probability of about 2.5% for a fluctuation of a sample where the true frequency is beyond the global sensitivity.