Background & Aims: SLC26A4 gene mutations are the second identifiable genetic cause of autosomal recessive nonsyndromic hearing loss (ARNSHL) after GJB2 mutations and are currently investigated in molecular diagnosis.In databases, several potential STR markers related to this region have been introduced. In this investigation, the characteristics and informativeness of D7S2425 CA repeat STR marker in SLC26A4 gene region was examined in five ethnic groups of the Iranian population. Methods: The locus was genotyped in 165 individuals of five different ethnic groups including Fars, Azari, Turkmen, Gilaki, and Arab using polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and fluorescent capillary electrophoresis. In this study, the results were analyzed by GeneMarker HID, Human STR Identity software, GenePop program, and Microsatellite Tools. Results: Analysis of the allelic frequency revealed the presence of 8 alleles for D7S2425 marker in the Iranian population, of which the 246bp allele at the D7S2425 locus with 0.30% frequency was the most frequent. The 93.9% observed heterozygosity of the Gilak ethnic group was the highest among all ethnic groups. Analysis of deviations of the Hardy-Weinberg equilibrium demonstrated that all the ethnic groups were in equilibrium (P > 0.05) for D7S2425 locus. Finally, analysis of PIC value revealed that the D7S2425 marker could be considered as a highly informative marker in each ethnic group of the Iranian population (PIC value above 0.7). Conclusion: Our data suggested that D7S2425 could be introduced as a highly informative marker in molecular diagnosis of SLC26A4 based ARNSHL by Linkage analysis