Background: The Functional Movement Screen (FMS) is a series of functional movement tests composed of seven tests designed to predict injury risk as well as sports performance. Therefore, the purpose of this study was to investigate the relationship between functional movement screen, core stability, and swimming performance. Methods: A total of 60 adolescents, boys aged 15 to 19 years, club-level swimmers participated in the present study. The Pearson and Spearman correlation methods were used to examine the relationships between variables (p≤0.05). Results: There was no significant relationship between any of FMS scores and swim performance (p>0.05). There was also no significant relationship not only between any of each individual FMS tests and core stability tests, but also between total core function and total FMS scores (p>0.05). Conclusions: Regardless of the fact that FMS is valuable in identifying individual weaknesses, compensations, asymmetries, and dysfunctional movement patterns, no significant relation was seen between FMS tests, swim performance and core stability. It seems that FMS is not a suitable assessment tool in assessing swimming performance. Therefore, this information is viable for those looking to do more research on the FMS as a predictor of athletic performance because it does not show results in favor of the FMS, according to this study.