The toxicity of purified ricin from Ricinus communis to rats was examined by histological and histochemical methods. Sprague-Dawley rats were injected intraperitoneally with 75㎍/㎏ body weight of ricin and were sacrified at intervals of 6, 24, 48 and 120 hours after injection. The major morphological changes, such as cloudy swelling, hydropic degeneration, necrosis, fatty change, blood congestion, increase of Kupffer cells in number and extension of sinusoids, were obvious in the liver of experimental group. These morphological changes of hepatic cells were mainly observed in both the periportal and midlobular region of hepatic lobule. The extension of sinusoids was obvious in the centrolobular region. And glycogen distribution of hepatic cells tended to decrease in the same region showing morphlogical changes as compared with the control group.