BACKGROUND: Epidemiology investigation showed that no worker drunk Maotai liquor for nearly 30 years died of hepatic diseases, and no obvious hepatic fibrosis and cirrhosis were found in 99 workers who had drunk Maotai liquor for a long period by epidemiology investigation and needle biopsy. The same finding was detected in rats that were drunk by Maotai liquor continued for 56 days. This study was to investigate the effects of Maotai liquor on the liver and its mechanism of preventing hepatic fibrosis. METHODS: After ingestion of Maotai for 56 consecutive days, male SD rats were killed for detecting the levels of metallothionein and malondialdehyde (MDA) in liver tissues. Rat hepatic stellate cells (HSCs) and human HSCs were cultured in vitro to observe the effect of Maotai on HSCs proliferation and collagen synthesis. After ingestion of Maotai for 14 consecutive weeks, the livers of male SD rats were harvested for pathohistological examination. RESULTS: The level of metallothionein in the liver of Maotai-induced rats increased by 22 folds, whereas the levels of hepatic lipid peroxide and MDA was decreased significantly (P<0.05) in Maotai-induced animals suffering from CCl4. Maotai demonstrated obvious inhibitory effect on proliferation of HSCs and the inhibition was concentration-dependent. Gene expression and protein secretion of collagens could also be inhibited by Maotai. In alcoholic group, typical liver cirrhosis was observed. In Maotai group, however, though fatty degeneration of hepatocytes and mild fibrosis of the interstitium were observed, no obvious hepatic fibrosis and cirrhosis were found. CONCLUSION: It might be an important mechanism of interfering the progress of hepatic fibrosis that Maotai increases the level of metallothionein in the liver and inhibits the activation of HSCs and the synthesis of collagen proteins.