BACKGROUND: Measurement of heart weight is important when investigating cause of death, but there is presently no satisfactory method of heart weight estimation by postmortem computed tomography (PMCT). METHOD: We investigated 33 consecutive cases that underwent both PMCT and autopsy between February 2008 and June 2014. Heart and left ventricular (LV) weights were calculated by PMCT morphometry. We used a simple method to estimate LV weight: We assumed that LV was an ellipsoid and multiplied its volume on PMCT with myocardial specific gravity. We then compared the various heart and LV weights using linear regression. The calculated and estimated LV weights on PMCT were also compared. RESULTS: It was not possible to predict heart weight at autopsy from PMCT (R2 = 0.53). However, heart weight at autopsy could be accurately predicted from LV weight calculated by PMCT (R2 = 0.77). In addition, there was a strong correlation between the estimated and calculated LV weights by PMCT (R2 = 0.92). Heart weight at autopsy could also be accurately predicted using the PMCT-estimated LV weight (R2 = 0.72). CONCLUSION: Heart weight at autopsy could be accurately predicted using a simple method in which LV volume was assumed to be an ellipsoid on PMCT.