Abstract: An experiment was conducted to study the effect of thiram on the serum enzyme activities, rate of tibial dyschondroplasia(TD), superoxide dismutase(SOD) and malondialdehyde (MDA) of liver in broilers. One hundred and twenty broilers were randomly allotted to three treatments ,with four replicate pens per treatment and ten chicks per pen. The three treatments were control, low level thiram(50 mg/kg) ,high level thiram(100 mg/kg). The results showed that thiram significantly improved serum AST, ALT, ALP activities (P< 0.05) and MDA of liver ( P< 0.05), increased rate of TD significantly, decreased growth performance and SOD level of liver significantly in broilers. It suggests that the thiram can damage liver function and cause the tibial dyschondroplasia in broilers.