It is widely accepted that the OO paradigm will signi cantly increase software reusability, extendibility, interoperability, and reliability. This is also true for high assurance systems engineering, provided that the systems are tested adequately. Software testing is an important software quality assurance activity to ensure that the bene ts of OO programming will be realized. OO software testing has to deal with new problems introduced by the powerful new features of OO languages. The objective of this article is to review some of the existing researches in OO software testing, in particular, the research at the University of Texas at Arlington.