Three patients (two females, one male) are reported with bilateral aniridia, Wilms' tumor, more or less moderate mental retardation, decreased catalase activity, and del 11p13. These and 34 case reports from the literature are discussed with respect to: sex ratio, maternal age, type of chromosomal imbalance and frequency of associated rearrangements, prevalence of aniridia and other eye disorders, predisposition to tumor development, genitourinary anomalies, growth and mental retardation, and catalase involvement. Possible gene relationship within the complex locus and with neighbouring 11p genes is discussed.