As the time goes on, the need for software applications is growing in every business, industry and for every event in life. One big challenge for software engineering is to test these increasing number of software applications. Software testing is a process to execute the software with the intent to verify its functionality. It also validates its process of development. Size of the program is one of the major concerns for tester during software testing. As thousands of lines of code are not easy to debug and test. The larger code makes the program complex. A program is analyzed to reduce program complexity. Program slicing is the program analysis technique that breaks the program code into smaller pieces. This research study proposed program slicing technique for object-oriented software testing to reduce program complexity. Object-oriented feature ?polymorphism? is taken as the subject for the program slicing techniques to minimize the overall testing cost and maximize the fault detection ability. This research proposed a program slicing technique for testing Object-Oriented systems by the use of adequacy measures code coverage and mutation analysis. Java programming language is considered for experiments of the proposed program slicing technique. Inclusiveness and precision metrics are used to evaluate the results of the experiment. These metrics are used for the assessment of test suite completeness and effectiveness.