Objectives were to determine the effects of recombinant bovine somatotropin (rbST) treatment of Jersey cows from −21 to 21 d relative to calving on rumination, activity, and lying behavior. Cows were assigned randomly to control and rbST (125 mg of rbST every 7 d from −21 to 21 d relative to calving) treatments. Cows (n = 50) were fitted with rumination/activity collars (SCR) and lying behavior loggers (HOBO) from −21 to 21 d relative to calving. Rumination and activity were recorded every 2 h and lying behavior was recorded every 1 min. Data were analyzed in 24 h intervals. Continuous data were analyzed by ANOVA using the PROC MIXED procedure for repeated measures with cows as the experimental unit. The model included treatment (control vs rbST), time (days relative to calving), and the interaction between treatment and time. Daily rumination time was not (P = 0.74) different between treatments in the prepartum, but rbST cows had reduced daily rumination time in the postpartum (rbST125 = 428.5 ± 17.0, control = 484.3 ± 16.7 min/d, P = 0.03). The interaction between treatment and time affected (P < 0.01) daily rumination time because from 0 to 7 d postpartum treatments did not differ, but in most days from 8 to 21 d postpartum control cows had greater daily rumination time. Treatment did not affect activity during the prepartum (P = 0.97), but control cows tended to have greater activity during the postpartum (540.3 ± 33.7 vs 499.1 ± 36.1 arbitrary units; P = 0.12). Lying time was not affected by treatment (prepartum-P = 0.34, postpartum-P = 0.72). Treatment by time interaction affected number of lying bouts in the prepartum (P < 0.01) and rbST cows tended to have greater number of lying bouts in the postpartum (rbST = 7.2 ± 1.1, control = 6.5 ± 1.6 bouts/day). Lying bout duration was not different in the prepartum (P = 0.86), but rbST cows tended to have shorter lying bout duration in the postpartum (rbST = 83.9 ± 3.8, control = 93.5 ± 3.7 min/bout; P = 0.08). Reduced rumination and increased lying bouts during the postpartum period among rbST treated cows may be associated with changes in metabolic and health status resulting from rbST treatment.