A numerical simulation system using the 3-dimensional finite element method (FEM) is established to reproduce the performance of the left ventricle during one cardiac cycle, which may ultimately provide useful information for medical diagnoses. This simulation system consists of a 3D-FEM mechanical model of the left ventricle based on mechanical properties of myocardial muscle and a circulatory system model which provides the preload and the after-load to the model of the left ventricle. In this paper, pressure-volume relationships estimated using the present system for various peripheral vascular resistances, aortic compliances and characteristic impedances are compared with those obtained from the corresponding canine experiments. It is shown that the two results coincide with each other to a reasonable accuracy.