Scenario analysis is a vehicle of separating concerns in the elicitation of users' requirements. It is also a means of requirements validation and verification. In the practical application of the method, a number of key activities must be supported by automated tools, which include: (a) the analysis of consistency among scenarios, (b) the analysis of the consistency and completeness of a set of scenarios with respect to requirements models, (c) the synthesis of requirements models from a set of scenarios, and (d) the generation of scenarios from requirements models for requirements validation. This paper presents an automatic toolkit that supports these activities. It adapts the idea of scenario analysis originally proposed in OO analysis to the structured analysis method.