The effects of vitamin C on ketamine anesthesia was studied. In normal rabbits the onset and duration of ketamine induced anesthesia were 6.0+/-0.5 and 36.0+/-0.9 min, respectively. Pre-treatment of rabbits with 30, 60 and 240 mg/kg, i.m. of vitamin C followed by ketamine 40 mg/ kg i.m. resulted in significant (p<0.05)decrease in the onset and increase in duration of ketamine anesthesia to 5.0 +/-0.06 and 37.0+/-0.7;4.0 +/-0.5 and 39.0*0.6;2.0+/-2.3 and 44.0+/-0.8 min, respectively. There was also significant (p<0.05)decrease in the heart rates in the animals treated with vitamin C and ketamine combinations. Serum analysis showed a significant (p<0.05)increase in blood glucose. The observed decreased in serum calcium and phosphorous following ketamine injection was prevented by pretreatment with vitamin C. These results suggest that vitamin C at higher doses could potentiate ketamine anesthesia in rabbits.