Description: Epidural anaesthesia is commonly utilized in veterinary medicine to allow diagnostic, obstetrical, and surgical interventions in the perineal region of domestic animals. Lidocaine is one of the most frequently used epidural anaesthetics. The following study was carried out to compare the time of onset and the duration of analgesia produced by the administration of lidocaine-MgSO4 combination with that produced by lidocaine-distilled water in the epidural space of sheep. Seven healthy adult (2 + 0.5 years of age) sheep (49+3 kg body weight) were used in this study. Significant difference (p<0.001) was noted for onset of analgesia between lidocaine-distilled water (2.07+0.73 min) and lidocaine-MgSO4 (4.57+1.27 min). The latter combination produced analgesia of significantly longer duration (174.0+12.19 min) than that of lidocaine-distilled water (53.42+4.7 min). There were no significant differences in standing time between groups. Also, there were no significant differences at the different post administration periods (min 10, 30, 45 and 60) compared to baseline values of heart rate, respiratory rate and body temperature for both groups of sheep. The utilization of the studied lidocaine-MgSO4 combination would allow obstetrical and surgical procedures of a long duration relatively soon after the epidural injection, without re-administration of the anaesthetic agent