JSE_V6_N3_RP2 A.V.K. Shanthi G. Mohan Kumar Journal on Software Engineering 2230–7168 6 3 13 20 Software Testing, Test cases, UML (unified Modeling Language), Genetic algorithm, and Activity Diagram In software development, testing plays an important role. Software testing is an important phase that ensures the quality of the software. This paper proposes a heuristic technique to test the software at the initial stage itself so that it will be easy for software testers to test the software in the later stages. Here test cases are an important entity or criteria by which software is being evaluated. Though Test cases can be generated by various approaches, Unified Modeling Languages attracts the recent researches and industrialists. This paper focus on test case generation by means of UML Activity diagram using Genetic Algorithm which best test cases are optimized and the test cases validated by prioritization. The test cases generated using our approaches are capable of detecting more faults like synchronization faults, loop faults unlike the existing approaches A case study is used to illustrate the approach. January - March 2012 Copyright © 2012 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=1787