Comparison of clinical and autopsy findings of the cases studied between 1984 and 1988, were made at the Department of Pathology of the Instituto Nacional de la Nutricion Salvador Zubiran in Mexico City. The goal was to determine the accuracy of clinical diagnoses. The total number of cases was 429. A decreasing number of autopsies as a function of time was observed. Thus, in 1985, 34.65% of the deaths was autopsied, whereas in 1988, the number dropped to 21.16%, overall mean of 27.31%. In 229 autopsies (53.8%), 353 findings of clinical significance were found; of these, 86 were in the main diagnoses and 267 in the causes of death. There were 171 overdiagnoses with therapeutic implications, 38 in the main diagnoses and 133 in the causes of death. Overdiagnoses and underdiagnoses were most common in infectious diseases, followed by respiratory and digestive diseases, while endocrinologic and rheumatologic diseases had the highest diagnostic concordance. It was also found that the diagnostic accuracy did not improve with time of hospitalization. A brief analyses of the probable causes of the decrease in the number of autopsies is made. It is concluded that, in spite of the great advances in clinical and technological knowledge, the high frequency of disagreements between clinical and anatomical diagnoses, indicate that autopsy continues playing a key role in the quality control of medical practice. This justifies by itself the performance of necropsies.