BACKGROUND Infection of Echinococcus multilocularis causes in humans the alveolar echinococcosis. Although the infection has world-wide distribution it is rarely detected. Diagnosis of alveococcosis is difficult because of not typical clinical picture and irregular results of radiological examinations suggesting neoplasmatic process which begins in the liver tissue or in the biliary tracts. The parasitic growth is slow, so the illness is quite often established in late invasion period. Treatment of long-lasting and late diagnosed infection is difficult and requires cooperation of parasitologists together with surgeons to avoid life-threatening organ dysfunction. METHODS We describe a young male patient, diagnosed, according to the radiological, immunological and histological examination results, infection of Echinococcus multilocularis, who was treated with not radical resection of pathologic mass together with persistent albendazole intake. The right hepatectomy was performed. In addition, visible cysts were removed from the left lobe of the liver in nonanatomical resection and suspicious calcified lesions in hepatoduodenal ligament were also removed. After the operation portal hypertension, with splenomegaly and symptoms of the liver cirrhosis occurred (thrombocytopenia, collateral venous circulation, first degree varices oesophagii). The portal hypertension probably could be a result of incomplete surgery due to extended parasitic infection and liver anathomical changes due to performed procedures, because the portal hypertension and it's further complications had not been observed before the operation. CONCLUSIONS Echinococcus multilocularis should be taken under consideration in differential diagnosis of irregular lesions within the liver. Lon-lasting invasion could be responsible for the irreversible secondary liver changes such as cirrhosis and portal hypertension. The surgery treatment (treatment of choice) is difficult and it's results depends on the invasion period the patient is operated on. After the surgery the patient requires careful follow - up, to detect early complications.