In a longitudinal study of senile dementia and healthy aging, the occurrence of serious falls was examined in participants with senile dementia of the Alzheimer's type (SDAT) (n = 44) and in cognitively healthy elderly control participants (n = 56) over a 4-year period. Falls occurred in 36% of SDAT individuals versus 11% of controls. The higher frequency of falls in demented participants was not explained by greater neurologic deficit nor by increased drug use compared with controls. However, males with SDAT who reported falls, had higher mean blood pressures and were more likely to be medicated than males with SDAT who did not fall. These differences were not observed in women. Falls in SDAT participants were associated with an increased rate of institutionalization. SDAT is an important risk factor for serious falls, and falls are associated with loss of independence in demented patients.