The color of postmortem lividity and control skin in 21 adult cadavers whose postmortem interval was within 72h, was measured by spectrophotometry in order to estimate the postmortem interval, objectively. The L *a *b * system, which has been widely used for the digital expression of skin color, was used and linear regression analysis was performed to determine the relationship between the postmortem interval and 31 color factors including L * (Value), a * and b * (Chroma and Hue) and C * (Chroma). The difference in Chroma between postmortem lividity and control skin (DeltaC * and DeltaC( *)/C(c)( *)) was only weakly correlated with the postmortem interval. We propose a new equation for calculating the postmortem interval using several color factors obtained by measurement of postmortem lividity, together with some autopsy findings that are known to affect the formation of postmortem lividity. The new equation makes it possible to estimate the postmortem interval within +/-4.76h.