Background: We hypothesized that fragmented QRS (fQRS) is an early marker of myocardial involvement in patients with cardiac syndrome X (CSX) which had updated term “Microvascular angina (MVA)”. Aim of the work: Therefore, we aimed to investigate the possible relationship between fragmented QRS (fQRS) and myocardial reserve in patients with MVA. Patients and Methods: Our comparative cross-sectional study was conducted on eighty-nine MVA patients divided into two groups according to presence or absence of fQRS. All patients were subjected to history taking, electrocardiogram (ECG), echocardiography, dobutamine stress echocardiography, coronary angiography and measurement of body mass index, blood pressure and serum lipid profile. Results: The prevalence of fQRS in patients with MVA was 61%; there were no significant differences in baseline echocardiographic measurments like LV mass, dimensions and ejection fraction (EF%) between patients with and without fQRS; on the other hand, patients with fQRS showed a significant decrease in myocardial reserve at Dobutamine stress echocardiography, and significant decrease in stroke volume and EF in comparison with patients without fQRS. fQRS was inversely correlated with cardiac output, stroke volume, ejection fraction as well as cardiac reserve, furthermore, number of leads with fQRS had a significant positive correlation with degree of reduction in cardiac reserve. Conclusion: In MVA patients, fQRS was correlated with reduced cardiac reserve; it has an important clue for microvascular and cardiac contractile dysfunction in these patients. Further follow-up data should be done on larger scale to show how to follow and treat those patients. Keywords: Microvascular angina, Fragmented QRS, Contractile reserve, Cardiomyopathy