The clinical features of 175 cases of essential tremor are related. This disorder is prevalent among a population of the Eastern Highlands of Papua New Guinea. It affects predominantly women in middle and old age; only 27 per cent of the cases were males. The disorder is slowly progressive and significant disability appears in elderly women when the trunk muscles are involved. Epidemiological studies have shown that the presence of tremor can be correlated with linguistic distinctions between high and low prevalence populations. Although only 30 patients reported a first degree relative with tremor, the syndrome would seem to stem from a genetic predisposition. In a number of patients essential tremor appeared to be associated with Parkinson's disease.