On 121 consecutive patients with coronary heart disease coronary angiography and quantitative left ventricular angiography was done with the view to aortocoronary bypass surgery. 24 (20%) had mitral regurgitation (MR) by angiographic criteria, 20 of them had MR grade I/IV, four had MR II/IV. In 23 out of 24 patients with MR quantitative left ventriculography revealed localized contraction disorders. MR was clinically diagnosed in 15 out of 24 patients. In eleven patients (48%) contraction abnormalities were localized in the inferior wall, in five cases (22%) in the anterior wall and in seven cases (30%) both in the anterior and posterior wall. Of the latter group patients with MR showed a significantly lower ejection fraction than patients without MR (p less than 0.05). Furthermore the MR-group showed larger akinetic areas, preferentially located in the inferior segments 0 degrees-240 degrees and in the anterolateral segments 60 degrees-90 degrees. Three vessel disease was more frequent in this group (43%) than in the group without MR (23%). Patients with inferior wall asynergy frequently showed combined stenosis or occlusion of the right and circumflex coronary artery. In conclusion, MR in coronary heart disease is most often associated with localized contraction disorders of the left ventricle; posterior wall infarctions, multiple vessel disease and large akinetic areas are more frequent. However, the hemodynamic significance of MR in patients with chronic myocardial infarction is usually insignificant.