Abstract : Background: Non Productive Time OT causes potential loss or deferment of revenue for the hospital and internal customer dissatisfaction. The quality tool Lean Six Sigma may help to reduce the non-productive time.Aim: To use elements of a six sigma model to reduce non-productive time in Gastro Intestine Surgery OT. It focuses on the reduction of NPT between Patient In time and Induction Begin time, Induction End time and Incision In time, Patient Out time and OT Readiness Time.Method: In a five phase study using DMAIC (Define. Measure, Analyze, Implement Control) model, business case, value analysis, brain storming, FMEA (Failure Mode Effect Analysis), RPN (Risk Priority Number) calculation identified causes and solutions. In six sigma analysis process sigma, target sigma and achieved sigma was calculated.Results: The null hypothesis of no difference in old and new Non Productive Time between Patient In time and Induction Begin time, between Induction End time and Incision and between Patient Out Time and OT Readiness Time was rejected using 2test since the p-value was below 0.05 at 95% confidence level. The process sigma was at 0.91, 0.96 and 0.67 which got improved to 2.55, 2.22 and 3.28 which was better than target Six sigma. Overall bottom line improvement was 4.8CR for the study period by bringing efficiency in the system. Conclusion: The six sigma project in OT resulted in reducing NPTs, helping to take more cases, patient discharge becoming more systematic, and reducing chaos regarding scheduling OT cases.