The effects of recombinant human growth hormone (rhGH) on protein metabolism were investigated. In the experimental study, 31 male Sprague-Dawley rats were divided into two groups. One group received 200 mU/day of rhGH for 3 consecutive days, before and after being burned (GH group). The other group received no rhGH as a control. Cumulative nitrogen balance after being burned was significantly higher in the GH group, and the rates of whole-body protein turnover, synthesis, and breakdown were significantly higher in the GH group. An increase of synthesis greater than that of breakdown resulted in an improved nitrogen balance in the GH group. Protein content of the liver and the gastrocnemius muscle were also significantly greater in the GH group. In the clinical study, 13 patients receiving esophagectomy for esophageal cancer were studied. Six of them received 24 U/day of rhGH for 5 consecutive postoperative days (GH group). Cumulative nitrogen balance on postoperative days was significantly higher in the GH group than in the control group. On the 3rd postoperative day, the rate of whole-body protein synthesis was significantly greater in the GH group; those of turnover and breakdown also increased in the GH group. The arteriovenous difference of amino acid composition revealed that uptake of branched-chain amino acids into the leg muscles was significantly elevated and that release of phenylalanine and tyrosine from the muscles was significantly reduced in the GH group. Hepatic function was not affected by the administration of rhGH, and rhGH inhibited the rise of blood urea nitrogen and total bilirubin after esophagectomy.(ABSTRACT TRUNCATED AT 250 WORDS)