Alveolar and cystic echinococcosis, serious parasitic diseases caused by larval stages of Echinococcus multilocularis and E. granulosus has been diagnosed in Slovakia for a long time. Study presents case of 49-years old patient with accidentally diagnosed one big (60 mm) and multiple small (2 - 24 mm) hypoechogenic structures localised in right liver lobe. According to positive serology to E. granulosus antigen and results of imaging examinations the patient was classifi ed as possible case of cystic echinococcosis and treated with mebendazole. Later, due to the worsening of clinical, laboratory and CT fi ndings surgical biopsy was performed and surgical biopsy and subsequent PCR examination of liver tissue confi rmed the diagnosis of alveolar echinococosis. Clinical picture of disease imitating cystic echinococcosis in presented case report, together with results of serological tests confi rmed importance of accurate differential diagnosis of echinococcosis. Each aspect of clinical and laboratory results should be considered responsibly, however, sometimes only molecular techniques can solve the problem of differential diagnosis.