The present study was conducted to examine the effect of recombinant bovine somatotrpin(${gamma}$BST), which was administered to cow to promote milk production, on bST levels in milk. Fourteen cows were divided cows were divided into two groups: 1) control cows received neither ${gamma}$bST nor vehicle, 2) treated cows were administered twice at two-week interval with 500 mg ${gamma}$bST each cow byj after lst injection. Milk samples were taken on day 0 (prior to injection), day 7 (7 days after lst injection), day 21 (7 days after 2nd injection) and day 35 (21 days after 2nd injection). Milk bST concentration was measured by the radioimmunoassay method. There was no statistical difference(p<0.05) in milk bST levels between two groups showing bST levels in the range of 1.8 ng/m/ to 3.1 ng/m/. That is, ${gamma}$bST administration did not increase bST levels in milk.