To prospectively evaluate diagnostic accuracy of dual source computed tomography (DSCT) for evaluation of aortic stenosis (AS) and aortic regurgitation (AR) with transthoracic echocardiography (TTE) as reference. We evaluated a total of 79 patients who underwent both DSCT and TTE, 40 with aortic valve disease as assessed by TTE, and 39 matched controls. Maximum aortic valve area (AVA) in systole was planimetrically measured with DSCT, and measurements were compared with TTE, as well as maximum regurgitant orifice area (ROA) in diastole. Dimensions of the aortic root and left ventricular parameters were compared. DSCT correctly identified 30 patients with AS [sensitivity 91%, specificity 100%, positive predictive value (PPV) 100%, and negative predictive value (NPV) 94%], and 32 patients with AR (sensitivity 94%, specificity 98%, PPV 97%, and NPV 96%). A significant correlation was observed between CT planimetric size of aortic valves area and TTE (r = 0.79; P < 0.01). Bland-Altman plot demonstrates a good intermodality agreement between DSCT and TTE with a slight overestimation of AVA by DSCT (+0.14 cm(2)). A significant correlation was observed between CT planimetric size of ROA (0.49 cm(2) +/- 0.40) and TTE classification of mild, moderate and severe AR (r = 0.79; P < 0.01). With receiver operating characterisitic curve analysis, discrimination between degrees of AR with DSCT was not very accurate within cutoff ROAs. A significant correlation was observed between methods in dimensions of aortic annulus (r = 0.87, P < 0.01), sinus of Valsalva (r = 0.91, P < 0.01), and ascending aorta (r = 0.92, P < 0.01), and in end-systolic volume (r = 0.82, P< 0.01), end-diastolic volume (r = 0.87, P < 0.01) and ejection fraction (r = 0.86, P < 0.01). DSCT can provide a simultaneous and accurate evaluation of the AVA, left ventricular ejection fraction and aortic root dimensions in patients with AS or AR, but measurement of ROA is not very accurate to differentiate severity of AR. DSCT can achieve an exhaustive and comprehensive preoperative assessment of patients with AS and AR.