This study was conducted to determine the frequency of medical disorders in people with mental retardation. The prevalence of mental retardation among adults, ages 20 to 50 years, living in Northern Sydney, was determined, and 202 persons were randomly selected for medical examination. Compared to the local population, the study group had significantly increased cardiovascular risk factors, rate of medical consultation, rate of hospitalization, and mortality. The research sample had an average 5.4 medical disorders per person, half of which had not been detected previously. We concluded that the provision of health care to adults with mental retardation needs to be improved.