Success in any relay race depends on the speeds achieved by the individual runners and the successful handover of the baton from each runner to the next. Choosing top sprinters is the easy part but there are many ways for the passing of the baton to go wrong. In this article, the knowledge and judgement required by the coach for a relay team are considered from a scientific point of view and an attempt is made to answer the question, 'Why do top relay teams drop the baton so often?'