Twenty patients undergoing AVR were subjected to this study and divided into the early and the late groups. 6 healthy adults were dealt as the control group. The EF, PER, 1/3 EF, TPE were compared among these three groups both at rest and during exercise. The detailed responses to the exercise were measured by %delta between at rest and during exercise. Furthermore, the LV function in the filling period were examined by the 1/3 FF and RFR at rest. This study suggests that although the left ventricular function and contractile reserve to the exercise remained insufficient in the early postoperative phase, nearly complete recovery of the reserve could be obtained in the later phase, while the left ventricular function in the rapid filling period was significantly decreased in both early and late postoperative phase.