Background and Objective: Non-specific chronic low back pain is the most common type of chronic low back pain. Rehabilitation to achieve a more rapid improvement in patients with chronic low back pain has always been taken into account. The aim of this study was to evaluate the effect of Pilates exercises on pain in female patients with non-specific chronic low back pain. Materials and Methods: 27 women with unexplained chronic back pain and hyperlordosis aged 30 to 50 years old were randomly selected and were equally placed in either experimental or control groups. In the pre-test, pain level, performance of patients and the degree of lumbar lordosis were assessed using Quebec, Oswestry questionnaires and Formetric 4D system. Patients in the experimental group participated in an 8-week Pilates exercises while patients in the control group did not participate in any specific program. Then, in the post-test, pain level, performance and the degree of lumbar lordosis of patients in both groups were measured. The patients in the experimental group participated in the modified Pilates exercises for 8 weeks, but those in the control group only received the conventional treatment in the same time period. Data analysis was performed using SPSS 16 and significant level of P≥0.05 was considered. Results: The results indicated a significant decrease in pain scores (P≥ 0.0001), a significant improvement in functional disability (P≥ 0.001) and decreased lumbar lordosis (P≥ 0.001) in the experimental group after 8-weeks of Pilates exercises compared to the control group. Conclusion: It can be concluded that Pilates exercises can decrease severity of pain, improve performance level and decrease lumbar lordosis in patients with chronic non- specific LBP. References 1- Bogduk N, Management of chronic low back pain. Med J Aust. 2004 180: 79-83. 2- Elbaz A, Mirovsky Y, Mor A, et al. 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