Software testing plays a crucial role in assuring software quality. One of the most important issues in the software testing research is the generation of the test cases. For the scenario-based software testing, the thin-threads, which are the usage scenarios in a software system from the end user?s point of view, are frequently used to generate test cases. However, the generation of the thin-threads is not an easy task. Scenario-based business model has to be manually derived or labor-intensive business analysis has to be manually carried out in order to extract the thin-threads from a software system. In this paper, we propose an automated approach to directly generate thin-threads from the UML artifacts. The generated thin-threads can be used to generate and to prioritize the test cases for scenario-based software testing.