We report herein an extremely rare case of retroperitoneal neuroblastoma occurring in a mother during her third trimester of pregnancy. A live male infant was delivered by cesarean section at 36 weeks gestation and 23 days later, the mother's tumor was curatively resected. Six months have elapsed since her operation and there has been no evidence of tumor recurrence. Adult neuroblastoma is an uncommon malignancy and, to our knowledge, there has been no case of this tumor occurring in pregnancy ever described in the English literature. The diagnosis, treatment, and follow-up of this neoplasm and its association with pregnancy are discussed in this report.