Three‐terminal dielectric measurements of the weak‐field permittivity have been carried out on single crystals of bismuth titanate (Bi4Ti3O12), which contained only ``narrow‐angle'' twin walls. The pseudo‐orthorhombic &egr;a, &egr;b, &egr;cin these twinned monoclinic crystals show strong dispersion in the frequency range 100 Hz‐1 mHz, and only above 1 mHz are the data representative of the intrinsic properties. The dispersion is thought to arise from space charge developed through the high conduction current at elevated temperatures and not from domain wall motion or damped piezoelectric resonance.