Abstract : The purpose of this study is to investigate the acute effect of chiropractic sacroiliac joint manipulation on core muscle strength in tennis players. 65 tennis players were approached for the study. A total of 50 tennis players with an average age of 47.8±11.4 who met the inclusion criteria and agreed to participate in the study were enrolled. After recording their sociodemographic information and time spent playing tennis, a test for abdominal and back core strength was conducted. Then, chiropractic sacroiliac joint manipulation was performed. A final test was conducted afterwards. The initial and final tests were performed by different chiropractors. The measurements for core muscle strength (abdominal and back) were performed using the Chattanooga Stabilizer Biofeedback Pressure device. Significant differences were found in abdominal and back core scores after chiropractic manipulation (p<0.05). Although males had higher back and abdominal core scores compared to females, this difference was not significant (p>0.05). Similarly, males had a longer time spent playing tennis than females, but this difference was not significant (p>0.05). Our study results indicate that core muscles, which are important for the health and performance of athletes, can be strengthened through chiropractic practices.