Most problems in building and refining a system can be traced back to errors in requirements. Poorly organized requirements, most often in natural language are among the major causes of failures of software projects. In this paper, we present a requirements analysis tool called RETNA and the technology behind it. RETNA accepts natural language requirements, classifies them, interacts with the user to refine them, automatically translates natural language requirements to a logical format so that they can be validated and finally generates test cases from the requirements.