BACKGROUND Middle managers have received little attention in extant health services research, yet they may have a key role in healthcare innovation implementation. The gap between evidence of effective care and practice may be attributed in part to poor healthcare innovation implementation. Investigating middle managers' role in healthcare innovation implementation may reveal an opportunity for improvement. In this paper, we present a theory of middle managers' role in healthcare innovation implementation to fill the gap in the literature and to stimulate research that empirically examines middle managers' influence on innovation implementation in healthcare organizations. CONCLUSIONS Extant healthcare innovation implementation research has primarily focused on the roles of physicians and top managers. Largely overlooked is the role of middle managers. We suggest that middle managers influence healthcare innovation implementation by diffusing information, synthesizing information, mediating between strategy and day-to-day activities, and selling innovation implementation. CONCLUSIONS Teamwork designs have become popular in healthcare organizations. Because middle managers oversee these team initiatives, their potential to influence innovation implementation has grown. Future research should investigate middle managers' role in healthcare innovation implementation. Findings may aid top managers in leveraging middle managers' influence to improve the effectiveness of healthcare innovation implementation.