Felton, C. A., Colazo, M. G., Ponce-Barajas, P., Bench, C. J. and Ambrose, D. J. 2012. Dairy cows continuously-housed in tie-stalls failed to manifest activity changes during estrus. Can. J. Anim. Sci. 92: 189-196. While pedometers are effective for estrus detection in free-stall herds, their efficacy in tie-stalls is not established. The objectives were to determine if pedometers equipped with a behavior tag for monitoring lying activity (AfiMilk Pedometer Plus Tag system) can accurately record cow activity, and if they can facilitate estrus detection in dairy cows continuously housed in tie-stalls. Nineteen lactating Holstein cows were subjected to estrus induction with prostaglandin F_2a, and 18 pregnant cows served as controls. Activity was monitored for 10 d using pedometers and 24-h video recording. Pedometer and video records were compared for 6 d surrounding estrus; stepping (rc=0.85; P<0.01), lying time (rc=0.94; P<0.01), and lying bouts (rc=0.89; P<0.01) were highly correlated. Progesterone concentrations confirmed that 17 of the 19 cows responded to estrus induction; 16 of those 17 cows ovulated. Changes in mean daily activity did not differ (P>0.05) between estrus-induced cows and controls, or in the estrus-induced cows in the 48 to 72 h preceding the day of ovulation. In conclusion, while the pedometers accurately recorded cow activity in lactating cows housed in tie-stalls, they could not facilitate estrus detection because cow activity did not significantly change during estrus.