ABSTRACTThe role of the autopsy is discussed in the study of the etiology of the current major causes of death (cardiovascular and neoplastic diseases) in developed countries. Evidence is accumulating for the importance of environmental factors in the etiology of these diseases. The study of regional differences in occurrence is described as a method of identifying specific factors. Maps are shown of mortality rates for all causes of death in Ontario counties for males aged 65–74 and 95+ during 1964–68. Some of the difficulties in obtaining data in this form, and in their analysis, are indicated. Regional mortality patterns can be interpreted by the use of associations with available regional socioeconomic measures, or by the use of regional data on trace‐metal levels in autopsy samples of human lung, rib, vertebra, kidney and liver. The methodology and the difficulties involved in the determination of trace‐metal levels in these tissues are discussed, as is the possible relevance of these levels to the study of degenerative diseases. All these considerations emphasize the valuable contributions of autopsy