Objective: The objective of this study was to understand the behavior and attitudes of professional athletes who participated in the 2016 Rio Olympics regarding nutritional supplements, energy drinks, and doping, within the context of sport nutrition.Methods: Our research team traveled to Brazil to collect the data for this study. Olympic athletes participating in the 2016 Rio Olympics were randomly selected to participate in this study. Participants were asked to complete a question-naire, and this activity took about 20 minutes. The survey contained nine questions including frequency of use, knowl-edge, and perception of nutritional supplements, energy drinks, and doping. Descriptive statistics were run to sum-marize the data collected and the results were displayed in frequencies and percentages. Data were expressed as means ± standard deviation and data were analyzed using a two-way ANOVA.Results: A majority of athletes (n = 129; 78.66%) gave positive responses regarding nutritional supplements while, 73 athletes (44.51%) had neutral opinions toward energy drinks. On the other hand, 118 athletes (71.95%) gave neg-ative responses to questions about doping. Relating to the frequency of product use, the results showed that a large percentage of athletes (n = 66; 39.76%) used nutritional supplements, and 59 athletes (35.98%) used energy drinks once per week. A majority of athletes (n = 157; 95.73%) re-ported that they were not doping. In the question relating to the main reason for consuming these products, the results showed that athletes use the products for different reasons. For example, 54 athletes (32.93%) believed that nutrition-al supplements could be used to improve speed, strength, and power. Similarly, 65 athletes (39.63%) reported using sports drinks for speed, strength, and power. Additionally, 98 athletes (59.76%) reported that they use doping for other purposes that were not listed on our questionnaire.Conclusion: Our results showed that response for taking nutritional supplements, energy drinks and doping and the reasons and the frequency of the use for taking these prod-ucts differ significantly (p ≤ 0.001).Nutritional supplements, energy drinks, and doping are being globally marketed to professional athletes for a wide variety of inappropriate uses. Consequently, it is important to educate athletes re-garding the proper use and potential physiological side ef-fects of supplements. Our study also indicated that coaches need to be educated and better informed in order to help athletes make appropriate choices regarding the use of these supplements.