Abstract The role of Th2 cytokines in human hydatidosis was evaluated in ELISA determining IL-5 and IL-6 production in PBMC cultures from 27 pharmacologically treated hydatid patients and from 13 uninfected controls. PBMC from patients produced large amounts of parasite antigen-driven IL-5, whereas PBMC from uninfected individuals produced none. In contrast, PBMC from patients and from uninfected controls produced large amounts of parasite antigen-driven IL-6. Immunoglobulin isotype analysis revealed that IL-5 production correlated significantly with IgE and IgG4 expression (IL-5/IgE r=0.5, P<0.05; IL-5/IgG4 r=0.6, P<0.05). The high IL-5 levels in supernatants from patients’ PBMC did not correspond to an increase in eosinophils. Neither IL-5 nor IL-6 production showed an association with the outcome of therapy. Overall, these findings confirm that the lymphocytes of individuals with Echinococcus granulosus infection contain Th2-like subpopulations.