To investigate the usefulness of serum cytokine levels in the diagnosis of active cystic echinococcosis, we evaluated the cytokine profile of patients with hepatic cystic echinococcosis in different cyst stages, CE 1-2 (active), CE3a-3b (transitional) and CE4-5 (inactive). Ex vivo assessment of Th1 (IL12, TNFalpha) and Th2 (IL4, IL10) cytokines in sera was carried out using ELISA. Percentages of positive samples and median levels of IL12, TNFalpha and IL10 did not differ significantly between groups. However, patients with CE3b cysts, a stage clinically unresponsive to treatments, had statistically significantly higher median levels of IL4 and percentage of positive samples for IL4. We conclude that the analysis of serum cytokine dosage, at least in its present form, is not useful as a marker of cyst activity. However, our results support recent findings suggesting the chronic activity of CE3b cysts and suggest that this might be partly because of a skewed Th2 response.