Retroperitoneal ganglioneuroma is a rare benign tumor, which is included in the neuroblastomas group. It can occur anywhere along the peripheral autonomic ganglion sites, and the tumor is often incidentally detected in asymptomatic patients or may produce symptoms related to the slow growing tumor. Surgical excision is the treatment of choice and the prognosis is good. We report a case of retroperitoneal ganglioneuroma, which was incidentally detected in the first trimester of pregnancy in a 29-year-old woman. Surgical resection of the ganglioneuroma was done at the time of cesarean section at full term without complications.