Organization’s performance depends upon the knowledge and intellectual resources including people, their work experiences, ideas etc. Knowledge management play an important role for an organization’s survival and competitive strength. There are different factors which reduce organizational performance by obstructing effective implementation of knowledge management in organizations i.e., organizational barriers, cultural barriers, technical barriers, personal barriers and environmental barriers. Purpose of this study is to find out the leading barrier(s) towards effective knowledge management implementation in Pakistan. For this purpose, questionnaires are used to gather data from the people of some organizations (teaching, medical and oil and gas). Percentage values of these barriers are 94.8, 94.4, 96.4, 96 and 94.4 respectively. Results show that knowledge management implementation is greatly affected by technological barriers and personal barriers and is suppressed by employ’s performance.