Objectives: Skeletal-muscular disorders affect the biomechanics of the human body, especially the lower extremity, with a negative effect on the biomechanics of exercise. The main aim of this study was to evaluate the effect of fatigue on the kinematic variables of knee joints during countermovement jumps in female students of physical education with valgus knee deformity. Methods:Fifteen subjects with valgus knee deformity and 15 healthy subjects without any damage in the lower extremities, particularly in the knees, volunteered to participate in this research. The healthy subjects were identical to those with valgus knee deformity in terms of demographic factors. All of them performed 3 countermovement jumps before and after the fatigue program. To create fatigue, a functional fatigue program was utilized, and the Borg scale was used to determine the level of fatigue in the patients. Results:The findings showed that maximum angular velocity and angular displacement significantly decreased in both the groups, after the induction of fatigue. The difference in the valgus degree, before and after fatigue, was greater in patients with valgus deformity as compared to the healthy subjects.Discussion: According to the results, the effects of fatigue on the kinematic variables in patients with valgus knee deformity are greater than on the healthy people. This could have been caused by the changes in the lower extremities and muscle length in patients with valgus knee deformity.