As a non-invasive method, ultrasound is a suitahle diagnostic procedure for routine in vivo examination of the human skin in dermatology. In this study 40 healthy test subjects were examined with a 20-MHz ultrasound scanner in order to determine the thickness and morphology of normal skin at 51 different sites. B-mode ultrasonography permits us to measure both the individual layers of the skin and deeper structures and to assess their definition and echogenicity. In both sexes the greatest skin thicknesses were found on: the shoulder-blade (mean thicknesses (mm), males 3.07/females 2.47); the upper back (m, 3.04/f, 2.85); the chin {m, 3.04/f, 2.69); the lower lip (m, 2.66/f, 2.50) and in the region of the lower back (m, 2.64/f, 2.39). Particularly thin skin was found on: the upper eyelid (m, 0.59/f, 0.64); the lower eyelid (m, 0.99/f, 0.86); in the groin (m, 0.97/f. 0.90); in the armpit (m, 1.01/f, 1.09) and on the forearm (m, 1.13/f, 1.00 mm). Knowledge of differences in the characteristic reflex patterns depending on the sex and age of the subject and the site of the skin examined forms the basis for assessment of pathological sonograms.