Background: Swedish health care organizations (HCOs) are changing using management concepts such as Lean, in attempts of improving efficiency, quality of care and work environment. Since there are pre-conditional challenges for operative managers to engage in change, HCOs tend to assign supportive functions such as change agents (CAs) to facilitate change. Research on the use of CAs in HCOs is sparse, thus the aim of this study explores role assignments and conditions of formally appointed CAs contributing to care process redesign. Methods: A purposive sample of three Swedish hospitals initiating Lean-inspired care process redesign during 2010-2011 was done. In-depth interviews were held with fifty-one key functions during change. Focus group interviews were conducted with thirty-eight health care professionals. Data were analysed by content analysis. Results: Top managers' goal was to have operative management responsible for change during care process redesign, with support from assigned CAs. Organizing of CAs varied concerning, e.g. their hierarchical positions, job descriptions and practices, and conditions to act as driving forces towards change. Being granted formal power, having earned legitimacy and credibility, clarity regarding roles and responsibilities in change; a good sense of timing and ability to build relationships and trust, were identified as beneficial for CAs to support change. Conclusions: Role assignment and organizing of CAs varies. A position closer to the operative levels, formalized and clarified responsibilities, earned legitimacy and timing support adaptation and alignment of planned change, such as Lean-inspired care process redesign.