The effects of additional leptin on the long type receptor (Ob-Rb mRNA) for adipocytes of new bo calf were tested by means of competitive reverse transcription polymerase chain reaction (RT-PCR).A sample of fine monolayer adipose cells were first obtained and recombination leptins of calf (5 ng/mL.12 h) were added.No additive was adopted as tester in the adipose cell.Total RNA was determined at 4,12,24,36,48 and 72 h,and duplicated three times in every treatment in the single factor duplicating test.The result,compared with the group of testers,was that the quantity of Ob-Rb mRNA in adipose cell cultures was also significantly higher (P＜0.01) at the beginning stage.Following this tendency,the quantity was gradually lower with cultured time going on in 12-24 h,and the quantity was in stable level (P＞0.05) from 48 to 72 h.It was shown that leptin could improve the level of expression of Ob-Rb in cultured adipose cells of new bo calf within a definite time.