The aim of this study is to investigate the effect of the game-based volleyball exercise program applied outside of physical education classes on the physical fitness abilities of primary school students. A total of 68 students (38 boys and 30 girls) from two classes participated in this study. Boy students, 20 of whom were in experimental group (age = 11.2 ± 0.8 years), 18 were in control group (age = 10.8 ± 1.2 years), and girl students, 18 of whom were in experimental group (age= 11.5 ± 1.2 years) and 12 girl students (age = 10.6 ± 0.9 years) were randomly assigned to the control group. Sit-ups, push-ups, bent-arm hang, trunk lift, shuttle run and sit and reach flexibility tests were performed to determine the level of physical fitness. Results from repeated measures analysis of variance showed a significant interaction on all physical fitness test scores in girl students. When girl students were considered, there was a significant interaction apart from the shuttle run and sit and reach test mean scores. It was seen that the service effect of a play-based volleyball exercise program improved the outcomes of both groups in boy and girl students after eight weeks of intervention. The experimental group showed a significant change in percentage in all physical fitness tests, except for the shuttle run and reach-reach test, in girl students compared to the control group. The findings show that although the game-based volleyball exercise program is effective on the physical fitness skills of primary school students, there is an improvement in the physical fitness skills of the children who do not participate in this training program. It is considered that this effect may be due to maturation or the differences in the physical activity levels of children.