We studied the effects of short-term replacement with human GH at three doses (0.124, 0.250 and 0.375 IU/kgBW/week) in 12 adult patients with GH deficiency (GHD). The patients were divided at random into three groups of 4 patients (groups A, B and C) and each group was treated with three doses of GH and placebo for 10 weeks in shifts of two weeks each. The replacement was started with one of three doses of GH given sc daily at 2100 h for 2 weeks, which was followed by placebo treatment for 2 weeks. The various doses of GH and placebo were then given alternately. GH treatment increased serum IGF-I and IGF-BP3 levels in all the patients examined although the responses were partly influenced by the order of GH treatment. When the data obtained with the same doses of GH in the three groups were combined, a dose-response was demonstrated. There was a close correlation (r = 0.726) between serum IGF-I and IGFBP-3. Serum triiodothyronine as well as non-esterified fatty acid (NEFA) levels also increased after GH replacement. Adverse side effects included edema in two cases and sleep distress in one case during the GH treatment at the highest dose of 0.375 IU/kgBW/week. These findings indicate that short-term replacement with GH at the doses of 0.125 and 0.250 IU/kgBW/ week is safe and effective in adult patients with GHD.