The impact of competence of project managers on project success of three selected Ethiopian companies-Elmi Olindo Constructors PLC, Ethiopian Airlines Group and International Livestock Research Institute is assessed. To achieve the objective of the research explanatory research design and quantitative research method are applied. Five point Likert scale questionnaire was administered to gather data from each organizations and managed to collect 52 responses. However, only 43 of them are considered for assessment as the remaining ones are found to be outliners. Three project managersâ€™ competences -knowledge, skill and personal characteristics- were used as explanatory variables for project success. Correlation and regression analysis was performed to achieve the research objectives. The correlation analysis revealed a positive moderate correlation between the independent and dependent variables. The result of the regression analysis also showed that project success is affected by the three mentioned competence variables; personal characteristics have the highest weight followed by skill and finally knowledge. The joint effect of the independent variables considered in the model has brought a 37% change in project success. Even though the study outcomes show projects managersâ€™ competence has an impact to project success, it is not to the highest effect. This may resulted from limited number of companies incorporated in the study and competence variables considered. Thus, future studies may increase their scope to comprise variety of organizations and additional competence variables