We studied the potential benefits of using lead V4R during routine exercise treadmill testing for patients undergoing district general hospital investigation for suspected coronary artery disease. Some 298 patients with known or suspected coronary artery disease, referred for exercise testing, had an electrocardiogram recorded with standard leads and had lead V4R placed in the V4R position. The exercise tests were interpreted using standard criteria and were reported as being negative, inconclusive, positive or adversely positive. The mean age of the patients was 57 years. Some 86 (29%) of the tests were positive: 12 of the 86 positive tests showed significant changes in lead V4R (14%). Of the 86 positive tests, 25 were adversely positive (29%) and, of these, nine had a positive V4R test (36%). Patients with V4R positive tests compared to those with V4R negative tests had significantly decreased exercise duration leads with ST changes and reduced workload. The finding of a positive V4R test indicated a significantly greater chance of an adversely positive exercise test result (p<0.001), with nine of the 12 positive V4R results (75%) being associated with adversely positive tests. There were no isolated positive V4R tests.