A two-phase epidemiological study of essential tremor was carried out by investigating a rural population aged over 40 years in 2 municipalities in southwestern Finland. In the first phase, the subjects answered a questionnaire as to whether they had experienced tremor during the month preceding the inquiry. In the second phase, the persons who had tremor often or fairly often, were examined clinically. The total prevalence of essential tremor, calculated on the basis of clinically established cases, was 55.5/1000 of the population aged over 40 years. The disease became more prevalent with advancing age and was, with the exception of the oldest age-group, more common in men than in women.