Aim: The aim of this study was to elucidate the assessment of mechanical valve function using 64 slice-multidetector computed tomography(MDCT). Method:In 20 patients(mean age=50짹12,M:F=14:16), 30 St.Jude mechanical valves(Aortic valve:Mitral valve=15:15) were evaluated using MDCT. We selected the images vertical and parallel to the mechanical valve. The valve orifice area(OA),the valve length by manual tracing and the opening and closing angle with protractor were measured.The OA and length of mechanical valve were compared with the manufacturer's values.Results:1.The OA based on manufacturer���s value and on MDCT were 3.4짹0.2cm2 and 3.4짹0.3cm2 in mitral portion and 2.1짹0.3cm2 and 2.1짹0.4cm2 in aortic portion, respectively. 2. Correlation coefficients between the OA based on manufacturer���s value and on MDCT were 0.746 in mitral portion and 0.836 in aortic portion, repectively(all p<0.001). 3. The length based on manufacturer���s value and on MDCT were 29.3짹1.99mm and 29.6짹1.65mm in mitral portin and 21.5짹2.1mm and 20.7짹2.3mm in aortic portion, respectively. 4.Correlation coefficients between the length based on manufacturer���s value and on MDCT were 1.145 in mitral portion and 0.790 in aortic portion, repectively(all p<0.001). 5.The each opening and closing angle on MDCT were 10.9짹0.6째 and 131.1짹3.2째 in mitral portion and 11.1짹0.9째 and 120.6짹1.7째in aortic portion.(Figure) Conclusion: Our results suggest that the MDCT is a powerful tool to assess the function and morphology of mechanical valve.