At Naerlandheimen Central Institution for mentally retarded a retrospective enquiry was conducted into causes of death. The enquiry included 186 deaths during the period from 1948 to January 1, 1990. The average age of deceased persons was 37.9 years. In approximately 40% of the cases infections were stated as the cause of death. All in all 32.5% of deaths were due to infections of the respiratory system, and diseases of the central nervous system constituted 8.9%. Cancer and coronary heart diseases, which dominate the statistics of causes of death in the average population, constituted respectively only 2.4% and 4.1% of the deaths.