We are interested in the precise localization of various DNA probes on the short arm of chromosome 11 for our research on the aniridia-Wilms' tumor association (AWTA), assigned to region 11p13 (Knudson and Strong 1972; Riccardi et al. 1978). For this purpose we have screened lymphocyte DNA and material derived from somatic cell hybrids from individuals with constitutional 11p deletions with a range of available probes: D11S12; calcitonin/CGRP (CALC1/CALC2); insulin (INS); Harvey ras 1 (HRAS 1); beta-globin gene cluster (HBBC); human insulin-like growth factor 2 (IGF-2); parathyroid hormone (PTH); human pepsinogen A (PGA). Using this material, it has been possible to map all probes used, except insulin, outside the region 11p111-p15.1, resulting in an SRO (same regional overlap) of 11p15.1-p15.5 for most probes. We found an SRO for PGA of 11p111-q12 and an SRO for CALC2 of 11p15.1-p15.5 or 11p111-q12. We have localised the insulin gene to band 11p15.1.