Background: Fibromyalgia (FM) and chronic fatigue syndrome (CFS) frequently overlap clinically and have been considered variants of one common disorder. It is characterized by diffuse musculoskeletal pain and discomfort. Many studies confirmed the increased risk of heart rate abnormalities in FM patients. So, the aim of this study was to assess p wave dispersion and QT interval changes in female Egyptians with fibromyalgia. Results: The mean QT and QTc dispersions were significantly lower in FM group compared with the HC group (p<0.001 for both). The minimum QT interval was significantly higher in the FM group (p<0.001). Regarding mean P wave dispersion, it was lower in FM group compared with the HC group but the result was not statistically significant (p=0.088). Relation between patient's results and types of graft used showed no statistically significant differences between them. Conclusion: FM patients had abnormal repolarization manifested as prolonged QTcd which makes them at higher risk for developing ventricular arrhythmias and sudden cardiac death.