This study investigates organizational structure, culture, and information technology as knowledge management (KM) infrastructural capabilities, and compares their significance and status quo in five medical research centers in Tehran, Iran. Objectives of this research were pursued by employing two statistical methods, regression analysis and Friedman test. Included in the study were 135 people (researchers and support staff) from five medical and healthcare research centers of Tehran. A survey questionnaire including 23 questions was utilized to examine organizational structure, culture and information technology indicators. And another 12 questions examined KM effectiveness. The Friedman test indicated that in terms of their status quo, the three studied KM enablers are at different conditions, with organizational culture having the best (mean rank=1.79) and IT the worst (mean rank=2.14) status. Moreover, it was revealed by regression analysis that organizational structure is believed to have the most significant impact (Beta= 0.397) on the effectiveness of knowledge management initiatives, while information technology gained the least perceived impact (Beta= 0.176).