This study investigated the relationship between nutritional knowledge and dietary behaviors of students at the University of Sports Ho Chi Minh City. A questionnaire was set up to assess the nutritional knowledge and dietary behaviors of 169 student-athletes (111 males and 58 females) with age ranging from 18 to 25. The collected data revealed that there is a close relationship between nutritional knowledge and the dietary behaviors of the students. Most students are aware of the importance of eating in moderation, and a healthy diet affects exercise results. The majority of the female (84%) and male (75%) athlete-respondents have a “good” level of nutritional knowledge. Besides, the 24-hours dietary recall survey was carried out on 43 students- marathon athletes (26 males and 17 females) aged 18-25. The results showed that the student-athlete-respondents perform heavy physical activities from Monday to Saturday every week. However, the amount of energy intake is considered inadequate compared to how many calories are needed for their daily training, even though they have day-offs. Therefore, there is a need to improve nutritional knowledge and dietary nutrition for student-athletes.