A report of a family with two half-brothers and a maternal aunt affected with the aniridia-Wilms tumor syndrome is presented. The proband showed a deletion of most of band 11p13 and of subband 11p14.1 of one chromosome 11, and the proband's mother and an older brother, both phenotypically normal, showed a balanced chromosomal rearrangement. This family demonstrates that deletion of a small chromosome segment (11p13-14.1) is responsible for the aniridia-Wilms tumor syndrome and, that in some cases, the syndrome can be familial.