Highly orienteda‐axis BaTiO3thin films were grown by pulsed laser deposition on (001) MgO substrates. The full width at half‐maximum of the (200) BaTiO3rocking curve was as narrow as 0.6°. A large hysteretic quadratic electro‐optic effect was observed in a transverse geometry at 6328 A˚. A birefringence shift up to 3×10−3was measured at an applied dc electric field of 1 kV/mm. It was found that laser repetition rate plays an important role on the surface morphology of the deposited films. ©1995 American Institute of Physics.