A trial was conducted to investigate the effects of dietary vitamin E (E) and thyme oil (TO) supplementation on the growth performance, lipid oxidation, fatty acid concentration of tissues and the serum lipoprotein levels of male broilers. Two-hundred day-old Ross PM3 chickens were assigned to one of five dietary groups (four replicates each). The control group received the basal diet. In addition to the basal diet, the four experimental diets included one of the following: 100 mg vitamin E/kg (E100); 200 mg vitamin E/kg (E200); 100 mg/kg thyme oil (TO100) or 200 mg/kg thyme oil (TO200). Birds that were fed the control, E200 and TO200 diets, exhibited the largest weight gain after a 42-day feeding period. The best feed conversion rate was found in birds that were fed the E200 diet. TBARS values of all of the dietary treatments, except the control, remained unaffected after a 42-day refrigeration period. The addition of thyme oil to the broiler feed led to a significant reduction in the saturated (SFA) and polyunsaturated fatty acid (PUFA) concentrations of the leg and breast tissues. The monounsaturated fatty acid (MUFA) concentrations in these tissues increased. The thyme oil supplementation also led to increased plasma levels of triglycerides, LDL-cholesterol and HDL-cholesterol in broilers. Based on the results of this study, it could be advised to supplement broiler feed with 200 mg/kg of thyme oil as an antioxidant.