In 25 patients with hGH deficiency, who had been treated long-term with hGH, the mode of hGH administration was switched from the conventional method (0.3-0.5 IU/kg/week, in two or three divided doses, intramuscularly) to daily subcutaneous injection at 1900-2100 hours with a dose of 0.46 +/- 0.07 IU/kg/week (equivalent to 14.7 +/- 2.0 IU/m2/week). After 1-3 months of this new mode of hGH administration, blood and urine were sampled at 0900 hours after overnight fasting. Blood glucose, plasma insulin, plasma IGF-1 and plasma total IGF (after extraction) were analysed in blood samples. IGF-1 and hGH were measured in urine samples. These measurements indicated that the dose studied was close to a replacement one, but might be slightly higher than the exact replacement dose.