Extrarenal nephroblastoma (ERNB) is a rare disease. We report a case of ERNB in a 4-year-old boy complaining of abdominal pain and vomiting. Imaging showed a retroperitoneal mass and left hydronephrosis. The mass was completely removed by surgery. The pathologic diagnosis was ERNB with favorable histology. Postoperative chemotherapy was administered for 24 weeks with actinomycin D, vincristine, and doxorubicin. No signs of recurrence were found for the next 3 years. We consider 53 reports of ERNB and our own. Median age at diagnosis was 42 months. The most common site is the retroperitoneal space (44.4%), followed by the uterus (14.8%).