This experiment was conducted to assess the comparative effects of dietary antibiotics and oregano essential oil (
OEO
) addition on growth performance, antioxidant status and intestinal health of broilers. A total of 384 one-day-old broilers were randomly allocated to 4 treatments with 6 replicates of 16 broilers each. The 4 treatments were: an antibiotic-free control diet (control), control + 20 mg/kg colistin sulfate and 20 mg/kg virginiamycin (antibiotics), control + 200 mg/kg natural oregano essential oil (
NOEO
), and control + 200 mg/kg synthetic oregano essential oil (
SOEO
). The experiment lasted for 42 d. Results showed that birds fed with OEO had greater (
P
< 0.05) average daily gain (
ADG
) and lower (
P
< 0.05) feed conversion ratio (
FCR
) than those fed with control diet during d 1 to 21. Besides, birds fed with NOEO had the greatest (
P
< 0.05) ADG in the four groups during d 22 to 42. The serum oxidative stress parameters showed that OEO improved (
P
< 0.05) the activities of glutathione peroxidase (
GSH-Px
), superoxide dismutase (
SOD
) and glutathione reductase (
GR
) of birds on day 21 and the activity of total antioxidant capacity (
T-AOC
) of birds on d 42. Relative to control, NOEO increased (
P
< 0.05) the activity of T-AOC in jejunum and decreased (
P
< 0.05) the level of malondialdehyde (
MDA
) in serum and jejunum. Moreover, OEO supplementation increased (
P
< 0.05) the concentrations of sIgA in duodenum and jejunum,
Lactobacillus
and total anaerobes in cecum, as well as activities of trypsin, chymotrypsin, lipase and amylase in duodenum, but restrained (
P
< 0.05) the amount of
Escherichia coli
. The NOEO supplementation increased (
P
< 0.05) total anaerobes of broilers on d 42 and the villus height to crypt depth ratio (
VH/CD
) of ileum. These results suggest that OEO improved antioxidant status and intestinal health of broilers which contributed to the growth performance improvement of broilers. Dietary OEO supplementation can be a promising alternative to antibiotic growth promoters for improving poultry production.