Previous studies suggest that microvascular abnormalities may contribute to the pathogenesis of Chagas’ heart disease. Coronary flow reserve (CFR) expressed by the maximum achievable flow relative to baseline flow in the coronary microcirculation, may be useful in identifying patients who may be developing cardiac manifestations of the disease. This study aims to assess the CFR in patients with indeterminate form of Chagas’ disease, and also to identify the determinants of CFR.