Background: Fibromyalgia is common in women causing spinal instability so they are prone to low back pain (LBP). Purpose: Determine the effect of core stability exercises on LBP in women suffering from fibromyalgia. Subjects: Forty women suffering from fibromyalgia and LBP participated in this study, their ages ranged from 25-35 years, their body mass index (BMI) ranged from 19-25 kg/m2, and they were selected randomly from the outpatient clinic of El-Eman hospital, Assiut Governorate. They were randomly divided into two groups of equal number; the control group (A) consisted of twenty women, who followed a self-care routine of good sleep, healthy diet, mental relaxation, and mindfulness for six weeks, and the study group (B) consisted of twenty women, who followed a program of core stability exercises of three levels for six weeks, added to the same self-care routine as group (A). Materials and methods: Assessment of LBP intensity and functional disability was done using the visual analogue scale (VAS) and Oswestry disability index (ODI), respectively, before and six weeks after interventions. Results: There were statistically significant differences (P < 0.05) in both VAS and ODI mean values when comparing pre- to post-study results in both groups (A & B). The intergroup comparison revealed a statistically significant greater improvement (P < 0.05) in VAS and ODI scores favoring group B over group A. Conclusion: Both self-care routine and core stability exercises are effective in decreasing LBP in women with fibromyalgia, but core stability exercises with self-care routine have a superior effect.