Recent studies show a susceptibility locus (DFNB1) responsible for non-syndromic neurosensory autosomal-recessive deafness (NSRD) mapping to the pericentromeric region of chromosome 13q. In order to better understand the frequency with which DFNB1 is the gene for deafness in our patient population and the role of DFNB1 in Caucasians, we performed a genetic linkage study with four microsatellite markers linked to DFNB1 in a total of 48 independent Mediterranean families, of which 30 and 18 were of Italian and Spanish descent, respectively. A maximum two-point lod score of 7.28 was found with marker D13S115 at a recombination frequency of theta 0.1. Significant lod scores were also obtained for D13S143, D13S292 and D13S175. Genetic heterogeneity was confirmed using the HOMOG program which indicated absence of linkage to DFNB1 in approximately 21% of the sample. This study clearly demonstrates that DFNB1 plays an important role in 79% of Mediterranean families with NSRD. Furthermore, results from multipoint analysis predict that the DFNB1 gene maps between markers D13S175 and D13S115 which are separated by approximately 14.2 cM.