Primary liver-cell cancer (PLC) mortality ratios, computed from death certificate records compiled by the National Center for Health Statistics, for the periods 1968-1971 and 1973-1976 were sorted by race, sex, urbanization, and region. From this sort, rural white males from the Southeast and the "North and West" regions were selected for comparison of mortality ratios and past dietary exposure to aflatoxin. Based on projections of recent aflatoxin contamination information back to the 1910-1960 period, and estimates of corn and peanut usage from household food consumption surveys relating to that period, the expected average daily ingestion of aflatoxin B1 for each group was calculated (Southeast, 13-197 ng/kg bw; North and West, 0.2-0.3 ng/kg bw). An age-adjusted excess PLC mortality ratio was observed for the Southeast population when compared with the "North and West"-10% excess PLC deaths at all ages, and 6% excess PLC deaths for the 30-49 year age-group-but although the difference was in the expected direction in relation to projected past exposure to aflatoxin, it was far from the manyfold difference that would have been anticipated from experiments with rats and from prior epidemiological studies in Africa and Asia. The remaining major portion of the PLC mortality in the Southeast may be attributed to many unidentified causes for which the two populations that were compared were not controlled, leaving in doubt the validity of any attribution of the excess PLC mortality to aflatoxin ingestion. A considerable excess over average US PLC mortality ratios was seen for all Orientals resident in the US and for urban black males. Occurrence of PLC in Orientals has been related to the presence of markers for hepatitis B virus in the blood serum of affected individuals.