Objective: The aim of this study is to investigate the effects of two different doses of racemic ketamine on block times in the ratsciatic nerve block model and to determine whether ketamine leads to nerve damage.Method: Sixty-four, Sprague-Dawley female rats were included into the study. Rats were anesthetized with ether and then thesciatic nerves were exposed by lateral incision on posterior approach. A total of 7 groups were formed, including Sham and Saline(0.2 mL saline) for the first step of the study. The other groups according to the test doses were: Group B (0.1 mL 0.5% bupivacaine+0.1 mL saline); Group K1 (0.1 mL ketamine 0.5 mg kg-1+0.1 mL saline); Group K2 (0.1 mL ketamine 1 mg kg-1+0.1 mL saline);Group BK1 (0.1 mL 0.5% bupivacaine+0.1 mL ketamine 0.5 mg kg-1); Group BK2 (0.1 mL 0.5% bupivacaine+0.1 mL ketamine1 mg kg-1). An investigator blinded to the groups evaluated the durations of proprioceptive, motor, and sensorial block. Afterneurobehavioral examinations, the sciatic nerves were removed on 8th days, and were analysed for perineural inflammation, ornerve damage. Results: Ketamine (0,5mg kg-1) combination with bupivacaine prolonged the durations of proprioceptive, motor and sensorialblock about %41, %23, %33 rates, respectively. Ketamine (1mg kg-1) combination with bupivacaine prolonged the durations ofproprioceptive, motor and sensorial block about %45, %37, %31 rates, respectively. While sole injection of ketamine to the sciaticnerve did not develop motor block, it provided a shorter proprioceptive block than other groups, and a similar duration for sensorialblock. It was seen that the changes in durations of block were not dose-dependent. There were no statistical difference betweengroups according to neurotoxicity. Conclusion: We believe that rasemic ketamine may be a good adjuvant in terms of sciatic nerve block, however further studiesare needed in terms of safety and systemic side effects in humans, in spite of the positive results of our study.