OBJECTIVE. The symmetric distribution of pulmonary vascular congestion and edema caused by left ventricular heart failure associated with severe mitral regurgitation as seen on chest radiographs is well known. To our knowledge, only eight cases have been reported in which congestion and edema were confined to one lung or a portion of one lung. The purpose of this study was to determine the prevalence of asymmetric findings in these patients. MATERIALS AND METHODS. Three radiologists retrospectively and independently reviewed the plain chest radiographs of 131 patients with severe mitral regurgitation admitted to our institution during a 3-year period. Radiographs showing asymmetric vascular congestion or pulmonary edema were identified. Clinical records of these patients were studied to exclude other causes of pulmonary disease. RESULTS. Radiographic signs of vascular congestion and edema were present in 117 (89%) of the 131 patients. In 12 (9%) of 131 patients, these findings were localized or predominant in the upper lobe of the right lung. None of the patients had predominantly left-sided involvement. CONCLUSION. Pulmonary vascular congestion and edema involving predominantly the upper lobe of the right lung in patients with severe mitral regurgitation occurs more frequently than previously thought. This information is useful in the differential diagnosis of right upper lobe abnormalities, such as pneumonia.