We report results of a search for C P T and Lorentz violation in B 0 − ¯¯¯ B 0 oscillations using inclusive dilepton events from 232 × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8 σ significance, compatible with no signal, for variations in the complex C P T violation parameter z at the Earth's sidereal frequency and extract values for the quantities Δ a μ in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26     yr − 1 to 2.1     solar   da y − 1 are also compatible with no signal.