The effects of vitamin C administration at varying time intervals on rectal temperature, respiratory rates, heart rates and sleeping time following xylazine anaesthesia was evaluated in rabbits. A total of 36 rabbits placed in six groups (A-F) with 6 animals per group each were used. Groups A and B were used as controls for vitamin C (120 mg/kg, oral) and xylazine (4 mg/kg, intramuscular) treatments, respectively, while groups C-F received vitamin C at four intervals prior to xylazine anaesthesia. The result of the study showed that vitamin C pre-medication prior to xylazine anaesthesia induced depression in respiratory and heart rates and a slight increase in rectal temperature. It also significantly increased sleeping time in rabbits (p<0.05). The lengthiest duration of sleep was observed among rabbits that received vitamin C 60 min prior to xylazine anaesthesia. Vitamin C administration 10 min prior to xylazine anaesthesia in rabbits induced a sleeping time three times the value compared to those animals that had received xylazine anaesthesia alone. However, the study did not observe a significant difference (p>0.05) in temperature between groups either before or after xylazine administration. It was concluded that vitamin C alters the clinical parameters as well as the sleeping time in rabbits under xylazine anaesthesia.