We aimed to confirm whether postmortem adrenal volumetric changes occur by measuring adrenal volumes on computed tomography (CT). Fifty-five adrenal glands from 28 subjects who died were included. All subjects underwent antemortem CT (AMCT) and postmortem CT (PMCT) within 94-1,191 min after death, followed by conventional autopsy. CT volumetry was performed using freely-available software. Differences between AMCT and PMCT adrenal volumes were evaluated statistically along with differences in the degree of volume change, elapsed time to PMCT, and presence of underlying malignant disease. The mean volume of the right adrenal gland decreased from 3.8 cm(3) on AMCT to 2.6 cm(3) on PMCT (P < 0.001); the left adrenal gland decreased from 4.2 cm(3) on AMCT to 3.1 cm(3) on PMCT (P < 0.001). Conventional autopsy revealed decreased intracellular lipid components in portions of the adrenal glands. No correlation between the adrenal gland reduction rate and the elapsed time from AMCT to death or from death to PMCT was observed (P = 0.99 and 0.79; P = 0.28 and 0.59 for the right and left adrenal glands, respectively). Significant differences in both the bilateral adrenal gland reduction rates and underlying malignant disease were found for the left adrenal gland (P = 0.015), but not for the right (P = 0.74). Adrenal volume reduction was observed on PMCT compared to AMCT. This highlights the need to further elucidate the mechanism of adrenal shrinkage during the agonal stage and after death. This may be explained by pathological findings of intracellular lipid depletion.