A cDNA encoding a novel member of the zinc finger gene family, designated zfOC1, has been cloned from the organ of Corti. This is the first transcriptional regulator cloned from this sensory epithelium. This transcript encodes a peculiar protein composed of 9 zinc finger domains and a few additional amino acids. The deduced polypeptide shares 66% amino acid similarity with MOK-2, another protein of only zinc finger motifs and preferentially expressed in transformed cell lines. Northern blot hybridization analysis reveals that zfOC1 transcripts are predominantly expressed in the retina and the organ of Corti and at lower levels in the stria vascularis, auditory nerve, tongue, cerebellum, small intestine and kidney. The human gene was mapped, using a human x hamster somatic cell hybrid panel and fluorescent in situ hybridization, to chromosome 12q24.3. Because of its relative abundance in sensorineural structures (retina and organ of Corti), this regulatory gene should be considered a candidate for hereditary disorders involving hearing and visual impairments that link to 12q24.3.