Use cases are a very effective means for capturing requirements in such a way that it is relatively easy to trace requirements into design and from design back into requirements. They have been successfully used in business systems for more than a decade. Real-time and embedded (RTE) developers have been slower to adopt this new technology. As RTE developers adopt object-oriented methods more completely, they are at the same time adopting use cases into their requirements capture workflow. However, because they are new, and because of some of the unique characteristics of RTE systems, use cases are more often misapplied than properly used.