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Study Objective: Cold Pressor Testing (CPT) is a known stimulus of the sympathetic nervous system (SNS). To better understand sympathetic contribution to coronary blood flow regulation in women with suspected ischemia and no obstructive coronary arteries (INOCA), we compared myocardial perfusion reserve during CPT stress cardiac magnetic resonance (CMR) imaging between women with suspected INOCA and reference subjects., Design: Prospective cohort., Setting: Academic hospital., Participants: 107 women with suspected INOCA and 21-age-matched reference women., Interventions: CPT stress CMR was performed with measurement of myocardial perfusion reserve index (MPRI), adjusted for rate pressure product (MPRI RPP ). Invasive coronary function testing in a subset of INOCA women (n=42) evaluated for endothelial dysfunction in response to acetylcholine, including impaired coronary diameter response ≤0% and coronary blood flow response (ΔCBF) <50%., Main Outcome Measure: MPRI RPP ., Results: Compared to reference women, the INOCA group demonstrated higher resting RPP (p=0.005) and CPT MPRI RPP (1.09±0.36 vs 0.83±0.18, p=0.002). Furthermore, INOCA women with impaired ΔCBF (n=23) had higher CPT MPRI RPP (p=0.044) compared to reference women despite lower left ventricular ejection fraction (64±7 % vs 69±2 %, p=0.005) and mass-to-volume ratio (0.79±0.15 vs 0.62±0.09, p<0.0001). These differences in CPT MPRI RPP did not persist after adjusting for age, body mass index, and history of hypertension. CPT MPRI RPP among INOCA women did not differ based on defined acetylcholine responses., Conclusions: Myocardial perfusion reserve to CPT stress is greater among women with INOCA compared to reference subjects. CPT induced a higher MPRI RPP also in women with coronary endothelial dysfunction, suggesting a greater contribution of the SNS to coronary flow than endothelial dysfunction. Further investigation in a larger cohort is needed., Competing Interests: Disclosure/Conflict of Interest Statement: The authors have nothing to disclose.