Two-dimensional echocardiography (2DE) was performed during 30-degree left lateral decubitus bicycle exercise in 52 patients who underwent cardiac catheterization for suspected coronary artery disease (CAD). Adequate echocardiograms were obtained in 39 patients (75%). Thirty-five of these patients underwent radionuclide angiography (RNA) with the same exercise protocol as for echocardiography. Exercise-induced or increased initial asynergy was considered to be a positive test by both 2DE and RNA. Echocardiographic, scintigraphic, and coronary angiographic data were compared to each other. Significant CAD (greater than 50% luminal obstruction) was present in 26 patients (66%). One of 15 patients with exercise-induced asynergy by 2DE had no CAD. Six 2DE and two RNA studies during exercise were falsely negative, sensitivity 76% versus 91%. Inclusion of RNA ejection fraction data would increase the sensitivity but decrease the specificity of RNA. Exercise-induced septal asynergy was far more frequently present by 2DE than by RNA (11 versus 6) in the 17 patients who had exercise-induced anterior asynergy by both methods. We conclude that it was possible to perform exercise 2DE in 75% of our patients. Exercise-induced asynergy on 2DE was specific (92%) for CAD. The sensitivity of 2DE in detecting CAD was less than that of RNA.