To determine the current frequency of discovering important diagnoses at autopsy, the diagnoses made in all complete or "no head" autopsies during 1994 at a major tertiary care transplantation referral center were retrospectively compared with the diagnoses made antemortem. Of 176 autopsies, 79 (44.9%) revealed 1 or more undiagnosed causes of death. Of the 123 undiagnosed causes of death, 13 were sole immediate causes of death, 72 were one of multiple immediate causes, 22 were intervening causes, and 16 were underlying causes. The causes of death were as follows: infections, 34; infarctions, 11; malignant neoplasms, 8; pulmonary emboli, 7; gastrointestinal ulcers, 7; hemorrhages, 6; thromboses, 3; amyloidosis, 1; genetic hemochromatosis, 1; and cardiac tamponade, 1. Of 35 autopsies of transplant recipients, 16 (46%) disclosed undiagnosed causes of death, compared with 63 (44.7%) of 141 autopsies of patients who had not received transplants. Approximately two thirds of the undiagnosed causes of death were judged to be treatable conditions. This and similar studies suggest that old-fashioned low-technology autopsies can uncover many important diagnoses missed by modern high-technology medicine.