A 15-year-old girl, who was evaluated for arthralgia of knees, was diagnosed as having brucellosis by serum agglutination and enzyme linked immunosorbent assay tests. Physical examination of the patient revealed massive hepatomegaly. Abdominal ultrasonography and computerised tomography showed a single large cystic lesion of the liver. The echinococcus indirect haemagglutination was positive at a titre of 1/1280. A giant hydatid cyst was removed with surgical intervention; in addition, she was treated with albendazole and antibrucellosis drug combination with success. Here, an immunocompetent adolescent case with brucellosis and concomitant hydatid cyst disease was reported to emphasise that the coexistence of both entities are infrequent but may occur due to increased prevalence of the diseases.