Hydatid cyst disease in bone is a rare one (0.5-2.5%) and 30% is seen in the pelvis. This disease is difficult to diagnose as symptoms are similar to the bone malignancy. Forty five years old female patient was admitted to another hospital with the complaints of pain in lower-right quadrant of the abdomen radiating to the right leg. She had a palpable mass in this region and was sent to our hospital with a prediagnosis of bone malignancies. During the physical examination, a mass about 8×10 cm semifixed to the right iliac bone was palpated. Serum tumor markers were within normal limits. Findings in magnetic resonance imaging was compatible with stage 3-4 hydatid cyst disease and also it was reported that cystadenocarsinoma should be considered in the differential diagnosis. Serological examination and fine needle aspiration biopsy were performed. Indirect hemagglutination test titer 1/2048(+) and biopsy results were consistent with hydatid cyst. Fifteen days prior to the surgery, the patient was given 10mg/kg albendazole treatment. Mass containing daughter vesicles caused bone destruction in iliac bone were totally scraped.