Improvement in left ventricular (LV) systolic function after aortic valve replacement (AVR) has been observed in patients with aortic valve stenosis (AS). However, the factors that predict such recovery remain unclear. We sought to identify the predictive value of the LV spherical shape for LV functional recovery after "isolated" AVR in patients with severe AS and LV dysfunction. We examined 90 patients with severe AS and LV systolic dysfunction by echocardiography before and after AVR. Patients with known coronary artery disease, significant aortic or mitral regurgitation, and other cardiac surgery were excluded. LV end-diastolic and end-systolic volumes indexes and ejection fraction (EF) were measured by the Simpson method. LV mass index was calculated by the area-length method. LV end-diastolic and end-systolic sphericity were calculated as the ratio of the minor axis to the major axis of the left ventricle in apical 4-chamber view. The postoperative EF was significantly associated with preoperative EF, end-diastolic and end-systolic volumes indexes, LV mass index, and end-diastolic and end-systolic sphericity (all p <0.001). Multivariate analysis revealed that preoperative EF, end-systolic volume index, and end-diastolic sphericity were independent parameters predicting postoperative EF. The sensitivity and specificity in predicting normalization of EF (> or =50%) after AVR were 65% and 83% for end-diastolic sphericity <0.57 and 68% and 91% for end-systolic sphericity <0.47, respectively. In conclusion, LV spherical shape and dilatation predicted poor LV functional recovery after isolated AVR in severe AS.