In 172 children and young adults aged 13-27 years dermatoglyphic deviations were investigated, as compared with the normal Prague population. The authors tested 116 hypertonic males, as compared with 130 male controls; 110 healthy women were compared with 56 suffering from hypertension. Using classical modern statistical tests, some significant deviations were found in the pathological groups. The authors detected a less frequent prevalence of ulnar loops and more frequent whirls on the fingers of hypertensive patients. The numbers of papillary lines on the fingers were higher, as compared with normal values. Higher "atd" values, although not significantly, were found a more frequent incidence of distal positions of the axial triradius. Deviations of some other signs on the palms such as the number of lines between triradii a and b, patterns in the interdigital spaces, on the hypothenar and thenar were less marked and there were moreover sex-conditioned differences. The observed changes suggest a marked participation of genetic factors in the aetiology of essential hypertension and they can be explained by laws of developmental mechanics of the papillary lines during embryogenesis. Dermatoglyphs, a non-invasive method, could serve as a screening indicator for the follow up of individuals in threatened families.