Cows (n = 210) were assigned to the following treatments: uninjected controls through 130 d postpartum; zero to high, uninjected through 60 d then injected with 14 mg of bST/d from 61 through 130 d postpartum; low, 5 mg of bST/d from 14 through 130 d postpartum; low to high, 5 mg of bST/d from 14 through 60 d then 14 mg of BST/d from 61 through 130 d postpartum; and high, 14 mg of bST/d from 14 through 130 d postpartum. Cows given 5 mg of bST/d (low and low to high treatments) yielded 1.2 kg of FCM/d more and high group cows yielded 1.3 kg of FCM/d more than control cows between 14 and 60 d postpartum. Cows given bST yielded 2.7 to 4.1 kg of FCM/d more than control cows during 61 to 130 d postpartum. Overall, control cows yielded 35.1 kg of FCM/d, and bST-dosed cows yielded 2.2 to 3.2 kg/d more FCM. Low group cows had improved pregnancy rate (80.0%) and conception rate (82.2%) compared with high group cows (57.2 and 60.3%). Neither pregnancy (70.0%) nor conception rates (71.5%) of controls differed from other groups. However, low group cows had first service conception rate of 57.8% compared with 34.3% for high and 38.2% for low to high group cows. First postpartum estrus was observed in high group cows about 13 to 16 d later than in low and low to high group cows, whereas low group cows came into first estrus 9 d sooner than controls. Cows of high group had lower body condition than controls (2.5 vs. 2.9), but other groups did not differ (2.7 to 2.9) from controls. Health was not adversely affected. Early postpartum bST administration at 5 mg/d increases FCM and, perhaps, reproductive performance of dairy cattle compared with herdmates.