This research develops a fuzzy analytic hierarchy process (FAHP) to investigate and prioritize the failures of knowledgebased business plans. Although the concept of failure investigation has been discussed in previous studies, its integration with knowledge-based business plans is not investigated yet. To fill this gap, this research is completed in three main steps as follows. Firstly, the general failures of business are developed from the previous literature. Secondly, the developed failures are investigated with regard to their availability in knowledge-based business plans. Finally, a FAHP is applied to prioritize the failures of knowledge-based business plans. According to the obtained results, lack of managerial experience, lack of written business plans and ineffective advertising are the most important reason of failing knowledge-based business plans. As the major implications of this study, the developed measures, methodology and obtained results assist managers, researchers and investors to determine the sources of failures in knowledge-based business plans.