We examined 482 livers, 377 from cattle and 105 from buffaloes slaughtered at a meat packing plant between April 1999 and November 1999, in Viamão, a town in the state of Rio Grande do Sul, in southern Brazil. The cattle slaughtered at the meat packing plant belonged to eleven towns: Cachoeira do Sul, Cachoeirinha, Capivari do Sul, Charqueadas, Encruzilhada do Sul, Ibiraiaras, Palmares do Sul, Pantâno Grande, Rio Pardo, Tupanciretã and Viamão. The buffaloes belonged to the following towns: Encruzilhada do Sul, Ibiraiaras, Parobé, Santo Antônio da Patrulha, and Uruguaiana. The occurrence rate of Fasciola hepatica was 10.34% for cattle in seven of the eleven towns included in the study (63.6%) and 20% for buffaloes in four of the five towns (80%). In terms of age, the occurrence rate was 81% for buffaloes with up to two years of life and 19% for buffaloes older than two years. The livestock from Cachoeira do Sul, Capivari do Sul, Ibiraiaras and Tupanciretã were not infected with bovine fascioliasis, and the buffaloes from Uruguaiana were not infected either. The studied areas may represent important endemic regions to fasciolosis, showing that zoonotic areas should be investigated.