The aim of this study was to determine the influence of soluble dietary fiber on the sports performance of basketball players, that is, on the neuromuscular endurance of vertical and sprint explosive strength, and on the aerobic and anaerobic cardiovascular endurance of basketball players. Also, the goal was to determine the influence of soluble dietary fiber on delaying fatigue in basketball players. The research included 18 young, adult basketball players of the same basketball team, in the competitive part of the season. The basketball players' eating habits and fiber intake were assessed based on a three-day food diary, and their consistency during the intervention was checked by 24-hour recall. Determination of morphological status was done along with measurements of sports performance. To measure neuromuscular endurance, we used tests to assess sprint-type explosive power (5 m, 10 m and 20 m sprint) and vertical-type explosive power (jump without preparation from a squat, jump with preparation, one-legged jump with preparation, maximum jump with preparation with swing hands, repeated jumps with preparation, and five repeated jumps from the feet). To assess cardiovascular endurance, we used aerobic endurance tests (BEEP test) and anaerobic endurance tests (300 m (15x20 m)). Research has shown that supplementation with 17 g of soluble dietary fiber for 4 weeks has no effect on the sports performance of neuromuscular and cardiovascular endurance. The research also showed a statistically significant delay in fatigue in basketball players. The intervention of supplementation with soluble dietary fiber proved to be ineffective on sports performance, and it reduced the feeling of fatigue in basketball players during the competitive season.