This paper presents the use of multithreaded processors in real-time architectures. In particular we will handle real-time applications with hard timing constraints. In our approach, events (e.g. timer interrupts, signals from the environment, etc) are distinguished into three classes according to the reaction times that have to be met. Since two of these classes are well known in real-time systems, we will focus on the new class, for which the special features of a multithreaded processor together with a real-time scheduler realized in hardware are employed. Doing so enables us to realize the handling of events from this new class in software while still meeting the demands on reaction time. Additionally, the predictability of the application and the ease of implementing them are increased. The processor, named MSparc, which we developed to support these features, is based on block multithreading and is outlined in this paper, too. We then present an architecture, designed for rapid prototyping of embedded systems, to show the feasibility of this approach. Finally, a case study shows the potential of multithreading for embedded systems.