<正> Objective: Morphine concentration measured in postmortem tissues may or may not reflect antemortem concentration. We measured levels of morphine in autopsied tissues to determine whether morphine distribution in morphine-dependent rats is altered after death. Methods: Solid-phase extraction was used to extract morphine from the samples

and morphine levels were measured at 0 - 96 h postmortem using gas chromatography. Results: The study of the morphine dependent rats showed a significant （P < 0. 05 ） increase of morphine concentration in postmortem cardiac blood

liver tissues and kidneys tissues. A significant increase was also observed at 72 h and 96 h postmortem in the brain

while morphine levels in cardiac tissues only increased at 24 h and 96 h postmortem. These changes were associated with an observed pH rapid decrease: pH of cardiac blood dropped from 7. 36±0. 15 to 6. 86±0. 09 （P < 0. 01）

pH of liver tissues from 6.98±0.04 to 6. 34±0.03 （P < 0.05）. Conclusion: The postmortem regional dist