The Authors studied correlations between angiocardiography and changes of R wave amplitude (delta R) during effort in 113 patients. They showed coronarographic evidence: 69 with stenosis greater than or equal to 70% of at least one major coronary vessel and 44 with no significant lesions. delta R values greater or equal than 0 were considered as pathologic. delta R appeared greater than or equal to 0 in 8 of 14 patients (57%) with single stenosis, 4 (28%) with abnormal wall motion (AWM). delta R increase or unchanged in 26 of 31 (84%) patients with double stenoses, 25 of them (81%) with AWM. delta R was greater than or equal to 0 in 22 of 24 (92%) with triple stenoses. In subjects with milk coronary artery disease (CAD) R wave increased or unchanged in 47% (19/44). Pathologic changes of R wave are highly frequent in CAD patients, especially in those with severe impairment. These changes, however, are not specific or costant because they appeared enough frequently in subjects with normal doronary vessels, and, moreover, R wave may decrease also in CAD patients with severe impairment. The Authors consider that evidence of delta R values greater than or equal to 0 may not be considered as a sign of CAD, but it must be evaluated with the other data showed by ergometric tests.