SummaryIn order to determine whether mercury from distant goldmining affected health in the districts of lranduba and Barreirinha, Amazonas State, Brazil, mercury in the scalp hair of 101 peasants (39 males and 62 females) was determined by cold vapour atomic absorption. In both areas fish is the major source of dietary protein. The average hair mercury content was 38.6 ppm (1SD = 14.1) in Barreirinha, where the diet contains a high proportion of carnivorous fish, and 5.6 ppm (1SD = 3.1) in Iranduba, where the diet contains more herbivorous fish. The levels found in women's hair in Barreirinha are particularly critical in view of the evidence that peak maternal hair mercury levels above 70 ppm are associated with 30% of risk of neurological disorder in the offspring, and that 5% risk may be associated with a peak mercury level of 10–20 ppm in the maternal hair (WHO 1990).The health of many people, and thus forest preservation, are threatened. An environmental monitoring and health programme is urgently needed for the Brazilian Amazon. Dietary assessment could be a useful indicator of the risk of mercury poisoning, if taken together with periodic analysis of mercury contents of commonly eaten fishes and of scalp hair, particularly that of young and pregnant women. Environmental monitoring is pointless if not directed at effective action; and a planning approach to this is suggested which includes a major educational component.