The furore surrounding the so-called ‘mad cow’ diseases is an important and controversial episode of recent years. Although it peaked several years ago, the topic is still of great medical significance, influencing the way members of the public think about and experience science and scientists. This study unit is just one of many that can be found on LearningSpace, part of OpenLearn, a collection of open educational resources from The Open University. Published in ePub 2.0.1 format, some feature such as audio, video and linked PDF are not supported by all ePub readers.