The effect of a synthetic C-terminal peptide sequence of human growth hormone, Leu-Arg-Ile-Val-Gln-Cys-Arg-Val-Ser-Glu-Gly-Ser-Cys-Gly-Phe (hGH 177-191) on glucose transport in adipocytes isolated from genetically-obese Zucker rats was investigated. The results showed that the synthetic peptide induced a reduction of basal and insulin-stimulated D[1-14C]-2-deoxyglucose uptake in isolated adipocytes. In comparison with the intact molecule of human growth hormone (hGH), the synthetic peptide at equimolar concentrations was found to be more potent. These findings are consistent with the suggestion that the functional domain responsible for the antilipogenic activity of hGH resides in the C-terminal region of the hGH molecule and the effect on glucose transport may contribute, at least in part, to the antilipogenic property of the peptide hGH 177-191 as well as of the intact hormone.