Abstract. Probabilistic model checking is a technique for formally verifying quantitative properties of systems that exhibit stochastic behaviour. In this chapter, we show how this approach can be applied to the study of biological systems such as biochemical reaction networks and signalling pathways. We present an introduction to the state-of-the-art probabilistic model checking tool PRISM using a case study based on the Fibroblast Growth Factor (FGF) signalling pathway.