The incidence of heart disease is increasing every year. One of the preventive actions is through early detection of the disease to take further action. Computer-Aided Diagnosis (CAD) helps doctors and cardiologists detect heart abnormalities seen in non-contrast cardiac CT images faster than manual detection. This study aims to detect the edges of non-contrast cardiac CT images. The method used is the Median and Laplacian filter algorithm using Matlab. The result shows that there is an automatic edge detection of non-contrast cardiac CT images. The conclusion obtained by the Laplacian filter with -8 kernel at its centre is clearer to detect edges of non-contrast cardiac CT images than the Median and Laplacian filters with -4 kernel at the centre. The study results are useful for medical image processing to facilitate the subsequent image analysis stage.