The purpose of this research study is to examine the Implementation of quality management systems in Iranian hospitals with particular emphasis on the role of top management commitment and leadership on quality management (QM) in service organizations. Taking both private and public Iranian hospitals as cases, a conceptual framework based on the theoretical dimensions and the findings is proposed. This study explores how contextual factors influence the implementation of Quality Management (QM) practices. It contributes to the contingency theory of quality management effectiveness. The analysis empirically examines the internal fit between QM and organizational structure, organizational culture and top management commitment as well as its external fit with environmental uncertainty. How these factors affect the implementation of quality management is also considered. Data were gathered from four hospitals from semi-structured interviews with hospital leaders, hospital managers and other staff who dealt with the implementation of quality management, fundamentally through semi-structured interviews. This was supplemented by document analysis. This research study demonstrates both internal fit and external fit affect implementation of quality management; however, top management commitment has a significant role in quality management implementation. Additionally, the findings offer insights for managers to customize quality management programs to achieve optimal performance benefits. This thesis makes an original contribution to the literature in integrating a contingency approach to quality management with an emphasis on distributed leadership as an approach to facilitating effective quality management in a hospital context.