Altogether 144 patients with various forms of retardation of growth aged 1 to 24 were investigated. Somatotropic function of the pituitary body was assessed by the results of a stimulation test with clopheline. A STH level was determined by a radioimmunoassay. Somatotropic function was undisturbed in an overwhelming majority of cases of genetically determined retardation of growth. Hormone therapy was not indicated in these cases as it could lead to unfavorable results: decreased indices of definitive growth resulting from the formation of antibodies to the growth hormone.