Branchio-oto-renal (BOR) and branchio-oto (BO) syndromes are autosomal dominant disorders, characterized by the presence of branchial, otic and renal anomalies of varying degrees of severity. We investigated the presence of EYA1 mutation in two unrelated patients with autosomal dominant hereditary deafness and congenital preauricular fistula. Case 1 had a mutation and polymorphisms, while Case 2 had polymorphisms with no mutations. In Case 1 we detected a heterozygous A-->G mutation at nucleotide 625 resulting in a serine to glycine substitution at codon 189 (S189G). The S189G mutation was not detected in 54 controls (108 alleles). Pure-tone audiometry showed bilateral mixed hearing loss of mild to moderate severity in Case 1. Case 2 had suffered from bilateral hearing loss since the age of 5 years and pure-tone audiometry showed bilateral moderate mixed hearing loss. These results suggest that the S189G mutation is a candidate mutation for BOR/BO syndrome.