The diagnostic accuracy of Doppler color flow imaging in the diagnosis of postinfarction ventricular septal defects has not been established. In this study, 43 patients with unexplained hypotension or a new murmur in the periinfarct period were evaluated with conventional two-dimensional echocardiography and Doppler color flow imaging. The presence of a ventricular septal defect was confirmed by oximetry, ventriculography, operative repair, or autopsy in each case. Both two-dimensional and Doppler color flow imaging were 100% specific in excluding a ventricular septal defect. Doppler color flow imaging correctly identified the 12 confirmed ventricular septal defects in this study (100% sensitivity), whereas any combination of two-dimensional criteria only correctly identified seven (58% sensitive) (p less than 0.05). Doppler color flow imaging is superior to conventional two-dimensional imaging in the diagnosis of a postinfarction ventricular septal defect. In addition, Doppler color flow imaging localized the septal defect, and thus guided therapy and technique for repair. Carefully performed Doppler color flow examination can exclude or result in the rapid diagnosis of a ventricular septal defect, which eliminates the need for further time-consuming confirmatory testing.