The prevalence of intermittent digital ischaemia (IDI) has been determined in a sample of 520 patients aged 20-59 selected from the list of a Hampshire general practice. Sixtythree cases were identified using a postal questionnaire (response rate 87 per cent) and, where possible (69 per cent), histories were confirmed by interview. The estimated prevalence of IDI was 8.3 per cent in men and 17.6 per cent in women. A minimum estimate based only on histories confirmed at interview was 5.0 per cent in men and 10.4 per cent in women. Of the 63 cases identified, 12 had consulted their general practitioner because of the problem but only two had been referred to hospital. We conclude that the course of IDI is generally benign.