Propolis, a bee product, can be regarded as one of the potential natural sources in folk medicine, displaying strong antimicrobial activity. Previous work showed that propolis extracts exhibited in vitro activity against Trypanosoma cruzi (Higashi and de Castro, 1994). Different formulations of propolis were administered to experimentally Trypanosoma cruzi-infected mice and the parasitemia kinetics and survival rate were monitored. The oral administration of ethanolic extracts up to 1.2 g propolis/kg per day or propolis offered ad libitum in the drinking water (up to 4 g/kg per day) or added to the food (up to 5 g/kg per day) did not interfere with both parameters. The differences between in vitro and in vivo trypanocidal activity of propolis and future perspectives are discussed.