One of the major tasts facing a transition economy is to create the competitive environment of a properly functioning market economy. It is widely belived that competition has positive effect on efficiency, but the theoretical and empirical support is quite scarce. The objective of this paper is to investigate the link between competition and efficiency for the Hungarian corporate sector during various phases of the transition process. We employ frontier production functions for exploring differences among groups of firms, and for identifying the typical adjustment process of each group separately throughout the transition period until 1997. Groups are defined according to industries, size, and ownership.