We describe a 28-year-old female who presented with metastatic spread of a suspected occult tumor. The diagnosis of alveolar echinococcosis was established by needle biopsy of the liver and ELISA. The patient's clinical symptoms initially decreased after treatment with mebendazole, but the lesions progressed during the following 6 months. Albendazole was not available in Austria. Because the synthesis of interferon gamma (IFN-gamma) and IFN-alpha is markedly decreased in patients with echinococcosis, we treated our patient with IFN-gamma while continuing mebendazole therapy. This combination halted progression of the disease during the 12 months of follow-up.