In today's dynamic environment, organizational leaders face many challenges that ultimately determine how effective they are in practicing their role. Making important decisions in the name of their organization, that consequently affect a large number of people, is part of their daily routine and, according to many, a central function of their vocation. Therefore, it can be concluded that managers approach this process individually, using a specific decision-making style. In this correlation study, the aim was to identify the relations between self-assessed managerial decision-making styles and managerial effectiveness assessments and self-assessments, as well as to find out whether there is a connection between decision-making styles and managerial leadership styles, assessed by their employees. The results revealed that managers who practice a passive-avoidant leadership style are also prone to using an avoidant decision-making style. That is, those who tend to avoid responsibilities and actions associated with the role of a leader also tend to avoid making decisions. Managerial effectiveness self-assessments were negatively associated with decision-making styles in those managers using an avoidant and spontaneous decision-making style. It is possible that these managers are aware of the ineffectiveness of stated methods and so they assess themselves accordingly. On the other hand, leadership effectiveness employee assessments, although highly related to their managers’ leadership styles, have been shown not to correlate with decision-making styles of managers.