Aniridia occurs as a phenotypically heterogeneous condition which may be inherited as an autosomal dominant disorder or as part of several systemic syndromes. It has been linked with the loci of chromosomes 1 and 2 and associated with the deletion of the p-13 band of chromosome 11. Aniridia may occur in a highly penetrant form in association with other ocular abnormalities with poor vision or in a more variable form with good vision. The recognition of a child with sporadic aniridia should alert physicians to the increased risk of development of Wilms' tumor.