Results from long-term follow-up studies “Enquete of Lausanne” presented, concerning incidence of suicide in old age of former mental patients. Among 1891 studied deaths, 107 (5.6%) known suicides occurred; suicide rate for all diagnostic groups, except mental retardation (only females) being considerably higher than the general Swiss population of the same age, especially for depressions, alcoholism, neurotic and psychopathic personality disorders.