Between January 1986 and December 1990 the prevalence of F. hepatica infection was studied in 5861 rural inhabitants of the provinces of Curico, Talca and Linares, VII Region, an hyperendemic zone of animal fascioliasis. Every one was screened by intradermal (IDR), complement fixation (CF), double diffusion (DD) counterelectrophoresis (CIEF), immunoelectrophoresis (IEP) and enzyme-linked immunoabsorbent assay (ELISA) tests. 366/1881 (9.3%) had positive IDR; 61 (1.04%) positive CF; 14 (0.24%) positive DD and 105/3838 (2.73%) positive ELISA and thus considered under suspicion to be infected. F. hepatica eggs were searched in stool in 241 of these persons. 37 cases were thus confirmed. Another 4 individuals with positive immunobiological tests and absence of the parasite eggs in stools were confirmed by duodenal intubation. 21 of the confirmed cases (51.2%) had less than 15 years of age. Women were more frequently infected than men (73.2% vs 26.8%). The 41 cases represent 0.7% of the surveyed population predicting 2000 cases among the total rural population of these provinces (300,000 persons). These results indicate that human fascioliasis is an important problem in the zone, perhaps much higher if family contacts of the index cases and symptomatic persons are included.