In this paper, we present a locking-based concurrency control scheme for object-oriented databases (OODBs). Our scheme deals with class hierarchy which is an important property in OODBs. The existing concurrency controls for a class hierarchy perform well only for specific environments. Our scheme is based on so called special classes and can be used for any applications with less locking overhead than existing works, for both single inheritance and multiple inheritance. In this study, we show the superiority of our scheme over existing works.