Abstract: Twenty two trials were conducted on 5 horses to compare the sedative effects of acepromazine and xylazine under same experimental conditions. Acepromazine was administered in the doses of 0.05 mg kg-1 I.V., where as xylazine was used in the doses of 0.5 mg kg-1 I.V. Acepromazine produced light to moderate sedation with an average sedation score of 1.55. Xylazine, on the other hand, produced moderate to deep sedation with an average sedation score of 2.45. Acepromazine produced less but longer-lasting sedation than xylazine. Acepromazine was also slower than xylazine to produce an effect. The sedation after acepromazine injection started on average at 19.55 min and maximum sedation was achieved at 33.64 min. The recovery from sedation started on average at 61.82 min but most animals still showed light sedation at the time of the last recording at 90 min after acepromazine administration. Xylazine produced immediate sedation (within 2 to 3 min of the start of injection). Recovery from sedation started on average at 27.73 min and full recovery was noted in 69.54 min. No sedation was noted 24 h after injection of both drugs. There was more individual variation in response to the onset of sedative effect of acepromazine than xylazine. It was concluded that the quality of sedation produced by xylazine was better than acepromazine and animals under the effect of xylazine responded less to visual stimuli/noise than after acepromazine.