Recently, the time allocated for physical education and physical activities in schools is gradually decreasing. Because schools, in order to get high scores on national standardized academic achievement tests, devote more time to other academic courses instead of devote time for physical education or physical activity (Rasberry et al., 2011). In Turkey, this problem is mostly seen at eighth grades that is the transition dass from middle school to high school. The purpose of this study is to examine the relationship between physical activity level, health-related fitness, academic achievement and academic self-concept at eight grade students who will attend the national standardized academic achievement test. In this research, the descriptive research method and purposeful sampling were used to determine the direction and level of change between the variables involved in the study. The relationship between variables was analyzed by Pearson correlation analysis (Karasar, 2017). The socioeconomic level that could affect physical activity and academic achievement variable were equalized. After the equalization process, seventy-six girls (51,7 %), seventy-one boys (48,3%) totally 147 eighth grade student have participated in the study. The personal information form, physical activity questionnaire for adolescents, Fitnessgram Test Battery, national standardized academic achievement test and the academic self-concept subdomain of Self-concept inventory-I was used for data gathering tools. In conclusion, there was a statistically meaningful, positive but weak correlation between physical activity, academic achievement, and academic self-concept level. In addition, there was a positive correlation between health-related physical fitness parameters and academic achievement score, while there was no significant relationship between health-related fitness parameters and academic self-concept scores in both girls and boys.