Wilms' tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR) syndrome is caused by deletion of chromosome 11p13, including the Wilms' tumor ( WT1 ) and aniridia gene ( PAX6 ) loci. Here, we report the first case of WAGR syndrome in Korea; the patient was a 2-year-old girl with bilateral aniridia from birth who presented with abdominal distention and mental retardation. Cytogenetically, she had deletion of chromosome 11p11.2-13. Bilateral Wilms' tumors were successfully treated by chemotherapy and surgery. She has been tumor-free for 19 months off chemotherapy with preserved renal function.