Hydropic degeneration of a uterine leiomyoma is common. Giant forms are uncommon. Positive diagnosis may be challenging because the differential diagnosis includes other rare uterine tumors such as leiomyosarcoma. Uterine localization, the leiomyoma volume, margins with adjacent structures are best evaluated at MRI. Final diagnosis requires gross and microscopic examination. We describe such a diagnostic challenge in a 46-year-old woman with a giant hydropic leiomyoma.