We propose a regression test case prioritization technique for object-oriented programs. We first construct an intermediate graph model of a program from its source code. When the program is modified, the model is updated to reflect the changes. Our constructed model represents control and data dependencies, and information pertaining to various types of dependencies arising from object-relations such as association, inheritance and aggregation. We determine the affected nodes in the model by constructing the union of the forward slices corresponding to each changed model element. A test case that covers a larger number of affected model elements is given higher priority. Our experimental results indicate that our approach on an average achieves an increase in the APFD metric value by 25.70 % as compared to a related approach.