Use cases have become increasingly common during requirements engineering, but they offer limited support for eliciting security threats and requirements. At the same time, the importance of security is growing with the rise of phenomena such as e-commerce and nomadic and geographically distributed work. This paper presents a systematic approach to eliciting security requirements based on use cases, with emphasis on description and method guidelines. The approach extends traditional use cases to also cover misuse, and is potentially useful for several other types of extra-functional requirements beyond security.