Autopsies are performed much less frequently in the elderly than in younger patients. Little information exists as to causes of death in the institutionalized elderly. The clinical diagnostic error rate documented by autopsy studies ranges from 6% to 68%. We analyzed the clinical and autopsy records of 234 patients who died during a 14 1/2-year period at our chronic care institution to determine the accuracy of clinical cause of death in addition to the pathologic cause of death. The most common causes of death included bronchopneumonia (33%), congestive heart failure (15%), metastatic carcinoma (14%), pulmonary embolism (8%), myocardial infarction (7%), cerebrovascular accident (6%), unknown cause of death (8%), and a miscellaneous group (9%). The highest diagnostic error rate was in the underdiagnosis of pulmonary embolism (39% antemortem accuracy rate). The most accurately diagnosed condition was cerebrovascular accident (92% antemortem accuracy rate). Pneumonia was correctly diagnosed antemortem in 73% of the patients studied. These data suggest that serious and potentially treatable illnesses are underdiagnosed in the elderly institutionalized patient and that there is valuable information to be learned by performing autopsies in the elderly population.