This paper explores the efficiency of banks in five South East Asian countries (Indonesia, Malaysia, the Philippines, Thailand, and Vietnam) using the non-parametric data envelopment approach and Tobit regression. The results indicate that efficiency has significantly declined over the period 1998-2004 indicating that the post-1997 crisis restructuring had a negative influence on bank performance. In line with the established literature on emerging markets, foreign banks appear to be more efficient than the domestic counterparts. However, state-owned banks exhibited greater efficiency than their local private sector peers. Among country-level factors, national banking development shows a strong and positive link with bank efficiency. The results are robust to different assumptions of bank inputs, outputs, technological changes, and national banking convergence.