Regression testing is a very costly process performed primarily as a software maintenance activity. It is the process of retesting the modified parts of the software and ensuring that no new errors have been introduced into previously tested source code due to these modifications. A regression test selection technique selects an appropriate number of test cases from a test suite that might expose a fault in the modified program. In this paper, we propose both a regression test selection and prioritization technique. We implemented our regression test selection technique and demonstrated in two case studies that our technique is effective regarding selecting and prioritizing test cases. The results show that our technique may significantly reduce the number of test cases and thus the cost and resources for performing regression testing on modified software.