Objective To investigate the effect of high power microwave (HPM) radiation on morphology of liver cells and serum cytokines in rats. Methods Adult male Wistar rats were exposed to 100 mW/cm² intensity microwave radiation as experimental group, and rats without radiation were designed as normal controls. The blood samples were obtained from the hearts to determine the levels of aspartate transaminase (AST), alanine aminotransferase (ALT), interleukin (IL)-6,IL-10 and IL-18 on 1 d,7 d and 14 d after HPM radiation. Finally the rats were sacrificed and the right leaf tissues of liver were obtained immediately under ice bath, and the hepatic tissue changes were observed under routine light microscope. Results There were inflammatory cell infiltration, scattered, and patched cell degradation, and necrosis in rat hepatic lobule on 1 d and 7 d after HPM radiation; the situation was improved on 14 d after radiation, but there were still cell degradation and dotted necrosis. Serum levels of AST and ALT in the experimental group were significantly higher than those in the control group on 1 d and 7 d after HPM radiation (P<0.05,P<0.01),but not on 14 d after radiation (P>0.05). Serum levels of cytokines IL-6 and IL-18 in the experimental group were significantly higher than those in the control group on 1 d and 7 d after HPM radiation (P<0.01),and the changes recovered somewhat on 14 d after radiation. Level of IL-10 was decreased after radiation compared with the control group, with significant difference found on 1 d after radiation(P<0.05). Conclusion HPM radiation can cause damage to liver structure and function, which might be associated with the changes of serum IL-6,IL-10 and IL-18 levels.