A total of 25 DNA markers located on the long arm of human chromosome 2 have been mapped by fluorescence in situ hybridization. This region includes the locus for Waardenburg syndrome, type I (WS1), recently found to result, at least in some cases, from mutations of the PAX3 gene. We have established that the chromosomal location of the PAX3 gene is within band 2q36. We also show that three markers in the distal 2q region, including the PAX3 gene, are deleted in a patient with phenotypic features of WS1 associated with a de novo deletion (2)(q35q36.2). The improved physical map of this region should facilitate linkage mapping and positional cloning of loci on distal 2q.