Cyclophilins are a family of proteins found ubiquitously in eukaryotes, many of which bind to the immunosuppressive drug cyclosporin A (CsA). CsA has been found to have anti-parasitic effects against a variety of helminth and protozoan parasites and this activity could be mediated via cyclophilin. In this study we characterize a full length cyclophilin gene from Echinococcus granulosus, the associated natural gene and expression pattern, and investigate the functional properties of the recombinant E. granulosus cyclophilin protein. In addition, the effects of CsA were investigated on E. granulosus protoscoleces in in vitro culture. The full length E. granulosus cyclophilin cDNA encodes a protein of 20 kDa and is encoded by a single gene (EGCyP-1) comprising 2 exons separated by a 31 bp intron. The gene is expressed constitutively in all E. granulosus life-cycle stages examined. Recombinant E. granulosus cyclophilin (egCyP-1) exhibited functional enzyme activity as an isomerase. Treatment of in vitro cultures of E. granulosus protoscoleces with CsA was found to be lethal to the parasites. No protoscoleces survived treatment with 10 μg/ml of CsA over 7 culture days, as determined by observing motility and the uptake of toluidine blue dye. Untreated protoscoleces remained viable for the duration of experiments. The survival of protoscoleces was CsA dose dependent. A concentration of 10 μg/ml CsA was 100% lethal while doses of 8 μg/ml and 5 μg/ml resulted in 82% and 32% killing, respectively, after 7 days in culture. The anti-parasitic activity of CsA may have the potential to be developed as a new therapeutic agent for treatment of cystic hydatidosis in humans.