The purpose of this study was to evaluate the effect of Pilates exercises on patients with chronic low back pain. For this purpose, 28 women suffering from chronic low back pain following informed consent participated in the study in two groups (control group: N=13, experimental group: N=15). The Pilates group performed Pilates exercises for 6 weeks and the control group received the routine treatment. Pain, disability and trunk flexor and extensor muscle strength were determined by visual analog scale (VAS), Oswestry low back pain disability questionnaire (ODQ) and ITOO test. Analysis of covariance and Turkey's post hoc test were used to analyze the data (P ?0.05). The results revealed that after six weeks of treatment with Pilates exercises, the mean pain (p=0.024) and inability (p=0.016) of the experimental group were significantly lower than the control group. Additionally, measures of trunk flexor and extensor muscle endurance of Pilates group were greater (P<0.001) than the control group. Based on the findings of this research, a series of Pilates exercises have positive effects on relieving pain, decreasing disability and increasing endurance of core muscles. Therefore, it appears that Pilates exercises could be more effective than routine methods in treatment of patients with chronic low back pain. These results and findings in addition to other studies demonstrated that Pilates exercises along with other treatment methods may have efficient outcomes for patients with chronic low back pain.