Various premorbid characteristics of a group of patients aged 50 or over suffering from paranoid psychoses (N = 54) were compared with those of patients of similar age suffering from affective psychoses (N = 57). (The diagnoses were those of the consultants.) The presence of deafness was investigated in the manner described by Cooper et al(1974). Using the discriminant function method, the diagnostic groups were highly significantly differentiated by six independent variables, which in combination predicted 40 per cent of the variance. These were: a 'schizoid personality' factor, the number of surviving children, precipitating events, deafness, family history and social class.