For any organizations achieving state of the art quality is important to become competitor in their field. Lean Six Sigma (LSS) helps organizations to get there. But, in some cases LSS implementation fails. Keeping that in mind this paper focused on the identification of critical failure factors for the LSS projects. Initially, we found out the failure factors through literature review which led to 44 factors. Then, a structured questionnaire was used to collect expert opinion on these factors for the manufacturing industry. Their response where checked for reliability and validity. Using, their response we ranked the 44 factors using topsis approach. From, the above study 16 critical failure factors were identified. This study may bring out the importance of the consideration of critical failure factors while implementing the LSS projects. In the conclusion section, future opportunities for research are identified.