Several epidemiological studies of amyotrophic lateral sclerosis have suggested that this neurological disease is uniformly distributed throughout the world. We report here the only study providing data on the incidence of this disease in France. It is based on a retrospective study of the Limoges region (Limousin) which contains only one university department of neurology. The study, conducted from February 1, 1977, to February 1, 1985, was not limited to in- and out-patients seen at this department, as we also contacted other non-hospital doctors who might have examined such patients. The average normal incidence was found to be 0.91 per 100,000 population. The male:female ratio was 1.16:1, and the median age of onset was 65 years. Median survival was 20.7 months.