Latissimus dorsi cardiomyoplasty was performed in 8 patients with dilated cardiomyopathy, normal coronary arteries and functional mitral regurgitation graded as mild or moderate. Patients were studied by equilibrium-gated angiography 1 week before operation and 4 months later. The functional mitral regurgitation was assessed by the ventricular amplitude ratio (VAR) derived from the Fourier amplitude image. One patient died of ventricular arrhythmia 5 months following operation. In the other 7 patients the clinical status improved from the New York Heart Association functional class III or IV to the functional class I or II. The left ventricular ejection fraction (EF) changed from 25 ± 7 to 26 ± 6%. The postoperative end-diastolic volume index was 78 ± 11 % of the preoperative value, and the VAR decreased from 2.01 ± 0.54 to 1.49 ± 0.59 (p < 0.005). Our results suggest that in patients with severely depressed myocardial contractility the main short-term effect of dynamic cardiomyoplasty should be the reduction in the left ventricular diameters. Secondary to this effect, the functional mitral regurgitation would be reduced and the cardiac performance improved, although the global EF would not be modified.