AbstractThis article describes a survey undertaken in 1976 of the prevalence of psychiatric illness in a total population of people aged 65 or over in the district of Clackmannan, Scotland. Using the Survey Psychiatric Assessment Schedule (Bondet al., 1980) prevalence rates of 7% for organic disorders and 22·5% for affective disorders and psychoneuroses were estimated for the total population of elderly people living at home and in institutions. This article reports logistic discriminant analyses which identify those variables which together predict the presence of psychiatric illness. Together age, functional capacity, civil status, the absence of an affective disorder or psychoneuroses and a visual impairment predict correctly whether a person has an organic disorder for 85% of the population. Together self‐perception of disabling conditions, feelings of loneliness, perceived lack of social contact, age, functional incapacity, lack of social contact, gender, visual impairment, presence of an organic disorder and hearing impairment predict correctly whether a person has an affective disorder or psychoneuroses for 81% of the populati