Background: Propolis is a resinous material collected by bees from various plants. It has antimicrobial, antioxidative, immunostimulative, and regenerative properties. We determined the scolicidal effect of propolis in different concentrations and various exposure times. Materials and Methods: Tubes containing Echinococcus granulosus protoscoleces were supplemented with different concentrations of ethyl alcohol extract of propolis. At the end of the incubation times, viability of protoscoleces was assessed by trypan blue exclusion test. We also applied 5 ml of 1 mu g/ml propolis intraperitoneally for determination of side effects and mortality rates. Results: We determined that 1 mu g/ml concentration of propolis killed all of the protoscoleces at the end of the 3rd minute. In the in vivo part of the study, intraperitoneal application of propolis did not cause any side effects or mortality. Conclusion: We concluded that this natural agent can be used as a potent scolicidal agent after studies which will determine in vivo efficacy and the effects on liver and biliary tree when injected directly into the common bile duct. Copyright (c) 2006 S. Karger AG, Basel.