Familial dysautonomia (FD) is an autosomal recessive disorder characterized by hereditary sensory and autonomic neuropathies. Although extremely rare in most populations, FD is common among Ashkenazi Jews (AJ), with a calculated carrier frequency of 1 in 30, based on disease prevalence. The gene for FD was recently identified as IKBKAP. One major mutation (IVS2 + 6T --> C) is responsible in >99.5% of cases among AJ. The purpose of this study was to determine the actual frequency of FD carriers in the AJ population in Israel and to determine whether carriers are more frequent among a subpopulation of AJ from Poland. The study group included 1267 Jews of Ashkenazi origin who were referred for routine DNA screening tests. These included 1100 individuals who were full AJ and 167 who were part AJ. None had a family history of FD. Mutation analysis for (IVS2 + 6T --> C) was performed by PCR amplification followed by restriction enzyme analysis. All positive cases were confirmed by DHPLC WAVE( trade mark ). Among the 1100 full AJ tested, 34 were found to be FD carriers (1:32). The incidence of mutation carriers was significantly higher in AJ of Polish descent (1:18) compared to AJ of non-Polish descent (1:99). Among the 167 individuals who were part AJ, there were 3 carriers (1:56). The incidence of FD among AJ, particularly those of Polish background, warrants population screening. Population screening may be performed by denaturing high-performance liquid chromatography.