A questionnaire about diarrhoea and how people react to it was answered by 400 people aged 16-70 years, most of whom were in employment (77% of respondents). There was wide variation in perceptions and reactions. Older persons and people in skilled trades were more likely to consider any increased bowel looseness or frequency of their usual bowel habit as diarrhoea, compared to younger persons and people in professional and managerial positions. Over half the respondents rated a single soft stool as diarrhoea, and almost a third accepted likewise an increased frequency of defaecation. The most unpleasant aspect of diarrhoea was considered to be incontinence with soiling of underclothes. At the onset of diarrhoea, 16% of respondents would not wait even a day or two but would go straight to a pharmacist, and 8% would go direct to a doctor. Persons in professional and managerial positions were less likely to attend their doctor straight away than people in other occupational groups. The findings show that for improved clinical management and public health surveillance, health professionals should not accept the term when it is used by patients, but seek details of their defaecation patterns and the form of their stools. Improved public education is needed as to self-help, appropriate treatment and when to seek pharmaceutical and medical advice.