There are limited data about the epidemiology of fascioliasis in Cuzco, Peru. We studied children 3-12 years old from six communities in the highlands of Cuzco to evaluate the epidemiology of fascioliasis; 227 children were included, one-half were female, the mean age was 7.5 (+/-2.6) years, and 46.2+/-% had one or more parasites, including Fasciola (9.7%), Ascaris (12.8%), Hymenolepis (9.3%), Trichuris (1.3%), hookworm (1.8%), Strongyloides (0.9%), and Giardia (27.8%). Fasciola was associated with the number of siblings in the household, drinking untreated water, and giardiasis. Eosinophilia was encountered in 21% of children and more common in those drinking untreated water at home and those infected with a parasite, but the differences were not significant. Eating water plants was not associated with Fasciola or eosinophilia. Fascioliasis and eosinophilia were common in the highlands of Cuzco. Fascioliasis was associated with socioeconomic factors and drinking water.