In this study, 96 broiler chicks aged 4 weeks were divided into 8 groups. The groups were; I.Control, II.Antibiotic, III. caffeic acid phenethyl ester (CAPE), IV.Antibiotic+CAPE, V.Ornithobacterium rhinotracheale (ORT), VI.ORT+Antibiotic, VII.ORT+CAPE and VIII.ORT+Antibiotic+CAPE. An inoculum of the ORT 3263/91 strain containing 3.8x108 CFU/mL was given as aerosol (Groups V-VIII). The administration of antibiotic and CAPE to the groups was started at the same time on the 17th day after giving the ORT. Enrofloxacin (10 mg/kg/day) was added to drinking water (Groups II, IV, VI, VIII), CAPE (10 μmol/kg) was applied as i.p (Groups III, IV, VII, VIII) for 6 days. ORT infection increased malondialdehyde (MDA) level and superoxide dismutase (SOD) activity in lung tissue, MDA, glutathione (GSH) levels and glutathione peroxidase activity (GSH-Px) activity in trachea tissue, while decreased GSH-Px and catalase (CAT) activities in lung (P<0.05). In lungs, the administration of antibiotic and CAPE alone and in combination to control group caused significant increase in the MDA level (P<0.05), significant decrease in GSH-Px and CAT activities (P<0.01). Antibiotic and CAPE alone and in combination caused significant reduction effect on the increased MDA level in the lung tissue due to ORT infection (P<0.001). In trachea, the administration of antibiotic alone and antibiotic+CAPE to control group caused the significant increase in MDA level (P<0.001). In the infection group, the administration of antibiotic and CAPE did not have a significant effect on the increased MDA level. The administration of antibiotic and CAPE prevented lung oxidative damage in the case of infection, but were not effective in trachea. Enrofloxacin and CAPE can be recommended to reduce oxidative damage in bacterial lung diseases in poultry.