Objective To study the effects of pentoxifylline (PTX) on antiinflammatory factor of nonalcoholic steatohepatitis (NASH) in rats. Methods Rats fed a standard diet for one week were randomly divided into four groups, control group(EM>n/EM>=10),12 weeks model group(n=10), 16 weeks model group(EM>n/EM>=10) and the PTX treatment group(EM>n/EM>=10). Two model groups and the PTX treatment group were then fed a high-fat diet. Meanwhile the rats fed a standard diet served as control group. After 12 weeks, the 12 weeks model group were sacrificed and the treatment group were given PTX ［16mg/(kgI>&#/I>8226;d)］ by intragastric administration. Then all the rats of other three groups were sacrificed at the end of the 16th week. Blood samples were collected aseptically from the abdominalis aorta and serum was separated with regular methods. Serum level of tumour necrosis factor α(TNF-α)was determined by ELISA. Serum levels of IL-1β and IL-6 were tested by radio immunoassay(RI). The immunohistochemical staining was perfored on the liver tissue slice, the expressions of IL-1β, IL-6 were evaluated. TNF-α mRNA was detected by RT-PCR. NF-κB binding activity was detected by electrophoretic mobility shift assay(EMSA). Results Serum level of TNF-α, IL-1βand IL-6 of model groups increased significantly than that of the control group. No statistical difference was found among the groups. The expressions of IL-1β，IL-6 were increased significantly in the model groups and the PTX treatment group (vs. the control group, P<0.05), while the expression of IL-6 was decreased in the PTX treatment group (vs. the model groups); The level of TNF-α mRNA was increased significantly in the 16 weeks model groups (vs. the co