The effects of long-term treatment of C57BL/6J (ob/ob) mice with a synthetic carboxylterminal sequence of human growth hormone, hGH 177-191, were investigated. Results indicate that the hGH 177-191 reduced the cumulative body weight gain, and decreased the adipose tissue mass. The lipogenesis in adipose tissues was significantly inhibited by the treatment with hGH 177-191. These findings support the suggestion that hGH 177-191 is the functional domain of hGH for the antilipogenic actions of the intact hormone both in vivo and in vitro. The hGH 177-191 peptide has the potential to be an effective compound for the treatment of human obesity and for the improvement of meat qualities in farm animals.