The WAGR syndrome is a multiple congenital anomaly-mental retardation syndrome caused by interstitial deletion of the distal portion of chromosome 11p13. It is a contiguous gene deletion syndrome, and WAGR is an acronym for the primary features: W for Wilms tumor, A for aniridia, G for genital anomalies, and R for mental retardation. Wilms tumor and male genital anomalies are caused by deletion of the WT1 tumor-suppressor gene, and aniridia is caused by deletion of PAX6 ocular developmental gene. Mental retardation is presumed to be a consequence of deletion of multiple as yet unidentified genes in the region. Individuals with the WAGR syndrome have a high risk for developing Wilms tumor and late-onset renal failure, and should be monitored for these complications.