Abstract: Clinicopathological findings of 25 cases, 18 males and 7 females, with alveolar hyda-tid disease of the liver were analyzed. The major symptoms were epigastric mass (96%), abdominal pain (40%), dyspepsia (24%), jaundice (20%) and portal hypertension (8%). The plain film roentgenogram of the abdomen in 4 out of 8 cases showed diffuse radiolucencies outlined by calcific densities over the hepatic region. Space-occupying lesions of different sizes in the liver were found in all of the 10 cases by radioisotopic scanning. Casoni's test was positive in 93.7% of 16 cases. Pathological findings were observed during laparotomy or autopsy in 22 patients. The gross type of large circumscribed mass was most common (54.5%) followed by the mixed type (22.7%) and the nodular type (18.1). Microscopically, numerous alveoli of various size and shape were revealed and the cuticular layer of aleeoli was characterized by laminated arrangement. Fibrogenesis and inflammatory infiltration were ussually seen in close vicinity to the alveoli or around the lesions forming a parasitic granuloma. The propagation of alveoli had shown both exogenous and endogenous budding. The diagnosis was preoperatively established in only 11 cases (44%). 13 cases (52%) were misdiag-nosed as cancer or hydatid cyst. Surgical operation was performed in 21 cases arid in none was the resection possible. 4 cases died of hepatic failure within 1-6 months postoperatively, 1 died of brain metastasis a year later and 14, survived for 1-3 years.