Background: Sports have a significant impact on people all around the world. Although sport brings a lot of joy, a sense of togetherness, and pride, it also involves ethically difficult issues such as doping. Doping in sports is a growing global concern that jeopardizes sports ethics, values, and integrity (The World Anti-Doping Agency WADA, a). Previous research has mainly approached the topic by understanding athletes’ motivation behind the decision to dope. Hence, there is a growing need to understand athletes’ attitudes and beliefs towards clean sports. Aim: This study aimed to comprehensively understand athletes’ attitudes and beliefs on reaching the top without doping and their beliefs on whether doping affects the results of competitions at the national and international levels. Also, it was examined whether variables such as age, gender, testing history, and sports have any distinguished matter on athletes’ attitudes towards clean sports. Method: A cross-sectional mixed-methods study explored athletes' attitudes and beliefs on clean sports. A total of 73 tested athletes (response rate 14,4%) completed a web-based "Assessments of Doping Control and FINCIS Activities" -survey. Results: In this research, athletes’ age, gender, testing history, and sports did not show any significance concerning athletes' attitudes towards reaching the national and international tops without doping. In the open-ended questions, athletes expressed trust in national-level competitions but had more suspicions about international competitions. Conclusion: The results suggest that the athletes in this research reported positive attitudes and beliefs in competing clean. However, it is challenging to determine whether athletes feel that they need to answer “correctly” and according to the values of clean sports. Therefore, it is important to continue studying athletes’ attitudes and clean sports.