Left ventricular function studies were performed on five patients with constrictive pericarditis. Functional data were obtained from intracardiac pressure measurements and cineangiocardiographic films. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), ejection fraction (EF), stroke work index (SWI), circumferential fiber shortening, and percent circumferencial shortening were significantly below normal values in the five cases. These changes are reflected mainly in the degree of pericardial restriction. Reduction in mean Vcf was also observed. Theoretically, the velocity of ventricular internal circumferential shortening is also affected by changes in ventricular volume or resting myocardial fiber length, however, in patients with constrictive pericarditis, reduction in mean Vcf suggests left ventricular dysfunction. Our clinical studies indicate that evaluation of mean Vcf is valuable in the assessment of postoperative prognoses.