An analysis is presented of the concept of 'disease' and its causes, held by one group of middle-aged women brought up in poor social circumstances. The diseases which the women talked about, and their ideas of cause, are shown to be the products of a particular medical and social history. The categories of cause which were favoured were infection, heredity and family susceptibility and agents in the environment. The women preferred to reject natural degenerative processes or the idiopathic: inevitability and randomness were both found frightening. It is suggested that the women's models of disease processes (though often factually incorrect) were in principle no different to those of advanced medical science, and no less sophisticated. The most notable features of their talk, however, were the salience of knowing about cause, the strain towards rational explanation and the importance of linking together life events. It is suggested that these are common human traits, which have implications for the interaction between doctors and patients.