The motivation to conduct the study was that external project managers have become more common the last decades. At the same time trust is considered to be a key factor for efficiency and good results for the organisation. The group members’ trust in the leader is built on past experiences of both the leader at a personal level, and the leaders’ relationship to the task. Trust can also be built over time, when the leader earns trust from the group members. Those conditions make it hard for external project managers to be trusted, because they don´t have earlier experiences of the group members, or a chance to build trust because of the limited timeframe. Earlier research on trust in the leader is solely based upon line organizations, which have different conditions than projects. A direct transferability to the project work should be questioned. You cannot assume that the relationship between project participants and external project manager is the same as between employees and managers in line organizations since they work in different forms of work. Upon those premises the research question became; Which factors have an impact on project participants' trust in an external project manager? To answer the research question, a qualitative interview study with an indirect approach was made. The sample consisted of eight respondents, all working for the same organization, active in the banking and insurance industry. To analyse the collected data a thematic analysis model was used. During the analysis a total of nine themes arose. Six of the themes were determined in advance based on the theory, competence, integrity, consistency, loyalty, openness and trust relationships. The remaining three themes that arose during analyse were, create team spirit, to fit in and external project managers. The results showed that project management skills, the courage to take transparent decisions, integrity, perform obligations, openness, to fit in and create team spirit, were factors that had impact on whether team members felt that they can trust an external project manager. The results also showed that research on trust, which was previously made in line organizations are not directly transferable to project environments with external project managers. Keywords: Project management, External project managers, Trust, Trust relationships