[Purpose] This study was carried out to determine the relationship between dynamic trunk muscle endurance and hamstring flexibility in patients with chronic ankle instability (CAI). [Subjects and Methods] A correlational study was conducted on twenty-nine non-athletic patients suffering from CAI of both sexes, with a mean age, weight, height, and BMI equal 22.24 ± 1.19 years, 74.69 ± 10.33 kg, 174.31 ± 8.82 cm, and 24.38 ± 2.24 kg/m², respectively were recruited for the study. Dynamic trunk muscle endurance and hamstring flexibility were assessed by bench trunk curl-up test and 90-90 active knee extension test, respectively. [Results] Correlation analysis of dynamic trunk muscle endurance and hamstring flexibility revealed a correlation coefficient r=0.403, p = 0.03; indicating there is statistically significant positive moderate correlation between the two variables. [Conclusion] According to the study's findings, A significant positive moderate correlation was identified between hamstring flexibility and dynamic trunk endurance in non-athletic patients with chronic ankle instability.