The project manager plays a central role in project integration and successful project completion. Leadership skills, especially knowledge-based leadership skills, are critical to project success as they enable the effective creation, sharing and use of knowledge. Project managers’ social cognitive, interpersonal and strategic skills contribute to effective knowledge sharing. The Lessons Learned method is generally recommended for knowledge transfer in projects, but its effectiveness and implementation are controversial. The aim of this study is to investigate project managers’ experiences with the Lessons Learned method in IT project management. The focus is on how these experiences influence knowledge transfer in IT projects. A qualitative research design was used to gain insight into the experiences of project managers. Eleven experts responsible for IT projects were interviewed in guideline-based expert interviews. The collected data was analysed using content structuring qualitative content analysis. The study found that project managers are responsible for knowledge transfer, but often do not perceive this task. Different perceptions of knowledge transfer methods were observed between traditional and agile training. The Lessons Learned approach showed unsatisfactory results and project managers defined their own methods. To improve knowledge transfer, project management standards should include clear tasks and support decision making. Generic models need to be integrated in the project management standards to ensure consistent approaches in practice.