Leiomyomas are very rare as retroperitoneal neoplasms. The pathogenesis of retroperitoneal leiomyomas remains obscure. A 42-year-old multiparous woman presented with a large abdominopelvic mass. At surgery, the uterus was displaced laterally to the right and the right kidney was displaced medially by three isolated large retroperitoneal masses. A total abdominal hysterectomy and complete excision of the retroperitoneal masses was performed. The histopathologic findings of the resected three tumors revealed leiomyomas without evidence of malignancy and the remaining surgical specimens were normal. This is the first case of three isolated large retroperitoneal leiomyomas without a uterine leiomyoma. The distribution of retroperitoneal leiomyomas in our case suggests that these may be of primary multifocal origin, rather than metastatic or parasitic.