Stress-induced abnormalities of regional left ventricular wall motion were assessed by cardiokymography (CKG) during the course of maximal treadmill exercise tests in 157 patients, of whom 122 subsequently underwent coronary angiography. Seventy patients had significant angiographic coronary artery disease and 52 were normal. Forty-one of the 70 patients developed greater than 0.1 mV ST-segment depression (ECG sensitivity 59%) and 52 of 70 patients developed abnormal systolic outward motion by CKG (CKG sensitivity 74%). Among the 52 normals, 36 had negative ECG stress tests (ECG specificity 69%) and 49 had normally sustained systolic inward motion by CKG (CKG specificity 94%). The stress CKG was normal in 15 of the 16 false-positive stress ECGs; the stress ECG was correctly normal in two of the three false-positive stress CKG tests. Only one normal patient had concordantly false-positive ECG and CKG tests. The predictive accuracy of concordant ECG and CKG interpretations was, therefore, higher than either test alone. These data suggest that regional wall motion abnormalities, which are sensitive and specific markers of myocardial ischemia, may be detected noninvasively by CKG. We concluded that CKG helps identify false-positive and false-negative ECG stress tests and improves the diagnostic accuracy of stress testing for detection of coronary artery disease.