In 196 children aged between 4 weeks and 16 2/12 years a sonographic investigation of kidneys was performed and put into relation to somatometric data including bodyweight (BW) bodylength (BL), length of the trunk and the upper and the lower limb, breadth of thorax and pelvic, head circumference, maximum cranial length and maximum cranial breadth. None of the children had signs of renal disorder. Morphometric data, as kidney length, width, depth, parenchymal areas in longitudinal and transverse sections and the prolate ellipsoid volume (PEV) were documented. The children were divided into five groups (group 1: 2-6 months, group 2: 6-31 months, group 3: 31-99 months, group 4: 99-131 months, group 5: 131-194 months). Mean values of all parameters were calculated. For each group a multiple regression analysis was performed and a regression equation of kidney length, parenchymal areas and volume was established. This method allows an individual determination of renal size and parenchymal mass.