We aimed to find out if addition of ketamine to the propofol–fentanyl –dexmedetomidine combination reduces the dose of all the drugs maintaining constant level of anesthesia and producing minimum effects on Transcranial Motor Evoked Potentials (MEP). It was a double–blind, prospective randomized controlled trial. A total of 60 patients, with ASA class I – III, undergoing spinal surgery under general anesthesia were enrolled and randomly divided into two groups; Group P received Oxygen + Nitrous oxide + Propofol + Fentanyl + dexmedetomidine infusion and group KP received ketamine infusion in addition to the above anesthesia technique. comparison of dose requirement of all the drugs were made between group P and Group K with out any fall in MEP. Mean of doses of drugs required in both the groups were calculated of all the drugs separately and compared in both the groups. SPSS 20.0 statistical system was used. Data was analyzed using student’s independent ‘t’ test and chi–square test .In group P ,mean of total dose of propofol used was 4.00 ± 0.85 whereas in group KP, it was 2.23 ± 0.70. Similarly in group P , mean of dose of dexmedetomidine used was 0.56±0.27 whereas in group KP it was only 0.22 ± 0.10 . In group P, mean of total dose of fentanyl used was 1.72 ± 0.42 on the other hand it was 1.02 ± 0.42 in group KP. On intergroup comparison, all these dose differences were found to be statiscally significant . ( P value < 0.001).Postoperatively recovery of patients were compared in both the groups and it was found that on intergroup comparison this difference was insignificant statistically.( P value of 0.301).Therefore it can be concluded that use of ketamine in small doses is better in terms of total requirement of all the other anaesthetic agents , when used as an infusion in patients undergoing spinal surgery without any effect on postoperative recovery .