Purpose: The aim of this study is the effect of core stabilization training (CST) at male swimmers in 10-13 ages on 50 m backstroke swimming time (ST), Biering Sorenson (BS) test, Flexor (FE) and Lateral Endurance test (LE) and Stork (SD) balance test parameters. Methods: 14 volunteer male swimmers who swim at the Yesilvadi Galatasaray Sports School were randomized to Experiment1 (D1) (n = 7) (age 11.57 ± 1.272 years, height 1.53 ± 0.04 m and weight 39.62). ± 3.55 kg) and Experiment2 (D2) (n = 7) (age 11.43 ± 1.272 years, height 1.53 ± 0.04 m and weight 41.43 ± 4.11 kg) after first measurements via the random method and 7 volunteered males were divided into the control group (F) (n = 7) (age 12 ± 1,155 years, height 1.53 ± 0.04 m and weight 41.43 ± 4.11 kg) and included in the study. CSA was applied to the D1 group athletes before swimming training 3 days a week (plank, side plank, reverse arm, reverse leg, reverse crunch, supine bridge, "V" sitting). The D2 group had only club swimming training and the K group had no training. The data were analyzed by Paired-Samples T Test and ANOVA test in SPSS 22.0 package program and the significance level was determined as p> 0.05. Results: Statistically significant difference detected in D1 group 50 m (ST) (p=0,012), BS (p=0,001), LE-right (p=0,04) and LE-left (p=0,022), FE values (p=0,004). Significant difference detected in D2 group 50 m ST (p=0,015) and BS test (p=0,000) result (p<0.05). No difference found in K group all parameters (p>0.05). As the result of final measurement results, significant difference detected at LE-right measurement between D1 group and D2 group, and LE-right and LE-left measurements among K group (p<0.05). Conclusions: As a result, it can be said that 8-week core and swimming trainings provide improvement in swimming point and endurance parameters and performance improvement can be achieved by applying to swimmers in 10-12 ages.