Two hundred and eighteen subjects, out of 250 individuals taken from a general practice register, returned completed questionnaires giving details about rest cramps, and a further 15 were contacted by telephone. The overall prevalence of rest cramps in the survey population was 37%. The symptom was more prevalent in older subjects. Rest cramps were most commonly experienced in the muscles of the leg, in 83% of the 86 cramp sufferers. Symptoms were usually present at night (73%). On average cramp episodes lasted for 9 min (95%CI 6.7-11.2). Most cramps sufferers experienced symptoms infrequently, but 40% had cramp episodes more than three times per week and 6% complained of at least one episode per day or night. Twenty-one per cent of cramp sufferers described their symptoms as very distressing. A minority, 32% of the 86 cramp sufferers, had reported the symptoms to a general practitioner although the 86 subjects self-rated their health more negatively than the individuals without muscle cramps. There was a significant, positive association between rest cramps and symptoms of angina or intermittent claudication although these two factors only accounted for 12% of the variance, suggesting that peripheral vascular disease may play a relevant but limited role in the aetiology of rest cramps.