The frequency of finger and palmar dermatoglyphic patterns was studied in 239 patients with familial deafness, their 155 unaffected parents and siblings and 456 hearing school-children. Differences between the deaf patients and controls, as previously reported, were not confirmed. The frequency of simian crease, including transitional forms, according to ethnic group (Arabs, Sephardi and Ashkenazi Jews) among 979 hearing school-children showed significant differences according to sex and ethnic group. Considering the sex and ethnic group differences, the deaf patients showed the highest frequency of bilateral transitional forms, while their unaffected parents and siblings showed the highest frequency of unilateral transitional forms of simian crease. The diagnostic value of these findings is discussed.