Background: Chronic mechanical low back pain a major health problem with dysfunctional consequences. Purpose: The purpose of this cross-sectional, correlation study was to investigate the relationship between core muscles endurance and functional lower limb performance in patients with chronic mechanical low back pain. Materials and methods: Twenty-six subjects with chronic mechanical low back pain were included in this study. Their mean age was 31.27 ±6.75 years, and mean body mass index was 25.89 ± 1.82 kg/m2. Researchers measured core muscles endurance with core endurance tests, and lower limbs` functional performance with hops tests. Spearman rank correlation coefficient was conducted to investigate the correlation between core muscles endurance and functional testing. Results: The findings of this study indicate that there was a correlation between right limb single hop and right-side trunk endurance; left leg single hop and trunk extension endurance; left leg triple hop and trunk extension endurance; percentage of improvement between right and left lower extremity triple hop and trunk prone endurance; and percentage of limb symmetry index during both lower limbs triple hop and trunk prone endurance (p<0.05). Conclusion: According to the results of this study, it can be concluded that in designing exercise programs for patients with chronic mechanical low back pain, core muscles endurance and functional lower limbs performance should be considered.