Twenty-one hepatic Echinococcus granulosus cysts (maximal diameter, 7.5 cm +/- 4.0) in 12 patients were aspirated and irrigated with hypertonic (20%) saline under sonographic guidance. All patients had signs and symptoms of a hepatic mass caused by the cysts, which had a prominent fluid component that appeared anechoic or hypoechoic, with marked enhancement of back wall echoes. The amounts of cyst fluid aspirated and of hypertonic saline used were 190 mL +/- 240 and 120 mL +/- 90, respectively. Separation of the endocyst from the pericyst and nonviability of scoleces were observed in all cysts. Mean hospital stay was 4.0 days +/- 3.4. Serial sonographic examinations revealed high-level echoes in the cyst cavity (heterogeneous echo pattern), which ultimately became uniformly echogenic (pseudotumor). After follow-up of 14.0 months +/- 5.5, maximal cyst diameter decreased to 4.1 cm +/- 3.1 (P less than .001). One patient died of unrelated causes; the remaining 11 patients experienced relief of symptoms and a decrease in liver span.