The aim of the study was to establish the effect of GH on immune functions in 22 healthy and in 11 uremic children, in vitro. Oxydative burst of granulocyte in the presence of GH measured by chemiluminescence and lymphoblast proliferation to GH and lectin stimuli were studied. Gene expression of GH receptor was analyzed with reverse transcriptase polymerase chain reaction (RT-PCR) method. The metabolic burst of granulocytes individually differed, specially in the chronic renal failure (CRF) group (60%) showed rather dose and time-dependent increase, the GH had only a priming effect. In 59% of the healthy children the GH stimulated the lympho-proliferative response itself or interaction with the lectin (ANOVA-test) and increased the spontaneous lymphoproliferation in 45% of the uremic patients. The GH receptor mRNA expression differed in the childrens lymphocytes, showing no correlation with the effect of GH on lymphoproliferation. The GH has a cytokine-like role in the regulation of the human immune system, and the GH treatment in uremic children is rather stimulating on immune functions.