The aim of this study was to compare the maximum-slope (MS) and dual-input one-compartment model (DOCM) methods in hepatic perfusion computed tomography (CT). A total of 37 patients with known or suspected liver disease underwent single-location dynamic CT after arterial or venous bolus injection of contrast material. Perfusion CT images were created by the MS (dividing the peak gradient of the time-attenuation curve by the peak vessel CT number) and DOCM-calculating from the equation dC ( L )(t)/dt = k ( a ) C ( a )(t - tau( a )) + k ( p ) C ( p )(t - tau( p )) - k ( v ) C ( L )(t)-methods. The perfusion parameters hepatic arterial perfusion (HAP), portal venous perfusion (PVP), and hepatic perfusion index (HPI) were determined. The PVP of the tumor-free hepatic parenchyma determined by the MS method was lower than that obtained by the DOCM method (P < 0.001) with both injections. HAP determined by the MS method was lower than that obtained by the DOCM method with venous injection (P = 0.001), although there was no difference between the methods for HAP with arterial injection (P = 0.154). Most of the perfusion parameters showed linear correlations between the two analytical methods. Except for HAP with arterial injection, the perfusion parameters obtained with the MS method were lower than those obtained with the DOCM method.