Introduction: People with chronic low back pain have functional disability associated with a decrease in productivity with major socioeconomic consequences. Resistance training is a form of exercise treatment that has been proposed to mitigate the problems caused by low back pain. It is recommended that the resistance training exercises focus on the posterior chain muscles and that the fragile condition of this population be considered. To the best of our knowledge, no study has yet investigated the effects of an acute resistance training session on pain and functional disability, considering such recommendations for people with non-specific chronic low back pain. Objective: Our aim was to assess the effects of a single resistance training session on pain and functional disability in people with non-specific chronic low back pain. Methods: 31 subjects of both genders with non-specific chronic low back pain took part in the study. Participants were randomized into two groups: the resistance training group (RTG) and the control group (CG). The RTG underwent a single exercise session. Results: The RTG showed a significant (p=0.001) decrease in perceived pain (5.9±1.6 versus 4.9±1.8) and a significant (p=0.016) decrease in functional disability (25.6±6.3 versus 20.5±4.1), after the resistance training session. The CG did not show significant differences (p=0.190) in perceived pain (6.9±1.7 versus 7.4±1.9)and in functional disability (26.8±7.8 versus 27.8 ±9.2), after the final assessment. The RTG showed a significant (p=0.001) increase in strength between the initial and final assessments (47.7 ±26.6kgf versus 60.2 ±31.4kgf) while the CG did not show any differences. Conclusion: A single resistance training session reduces pain and functional disability in people with chronic non-specific low back pain.