Background Assessment of coronary flow is only performed during pharmacological tests. Supine bicycle tests permit the visualization of coronary flow assessments during exercise. Purpose To assess the parameters of coronary flow in the left anterior descending artery (LAD) during exercise, which could be a sign of significant LAD narrowing. Material and Methods A total of 253 patients were enrolled: Group 1, 186 non-selective participants before undergoing a coronary angiography; and Group 2, 67 controls without coronary artery disease (CAD). All the patients performed a supine bicycle echocardiography test. Coronary flow velocities and coronary flow velocity reserve (CFVR) were measured at the mid-segment of the LAD during exercise. Patients in Group 1 underwent a coronary angiography. Results In comparison with participants without significant LAD stenosis, patients with LAD lesions had a lower δV (16 ± 21 vs. 27 ± 20 cm/s, P < 0.04) and a lower CFVR (1.5 ± 0.8 vs. 2.0 ± 0.6, P < 0.004). In comparison with patients without significant proximal LAD stenosis, the patients with proximal LAD lesions had a lower flow velocity at the peak of exercise (49 ± 32 vs. 61 ± 19 cm/s, P < 0.02), a lower δV (13 ± 19 vs. 26 ± 22 cm/s, P < 0.004), and a lower CFVR (1.4 ± 0.6 vs. 1.9 ± 0.7, P < 0.0001). In comparison with the control group, the patients with LAD stenosis had a lower flow velocity at the peak of exercise, a lower δV, and a lower CFVR. Conclusion Non-invasive CFVR measurement in the LAD could provide valuable additional information to a conventional echocardiography exercise test. In routine clinical practice, CFVR is sufficient for a diagnosis of severe stenosis.