We conducted this study to rank conflict of interest (COI) actors in Iran’s health system. Based on a review of relevant literature, we extracted a list of 27 actors within seven categories who play roles in the COI in the health system. We considered three criteria for ranking the actors: the actor’s interest, power, and authority concerning COI. Each actor scored one to five on the Likert scale in every criteria. Using descriptive statistics, each actor’s mean and standard deviation of its scores were calculated in these three indicators. The actors were ranked using the fuzzy TOPSIS method. The results showed the leading players in abusing the COI in the health system of Iran are the “Food and Drug Organization” and the “Parliament.” The role and capacity of civil society and nongovernmental organizations as essential arms of oversight and transparency should not be overlooked. The government needs to enhance its efforts, we envisage, to utilize the capability of these actors by opening a dialog with them and providing the necessary training for COI.