OBJECTIVE To investigate effects of in ovo ghrelin administration on serum malondialdehyde (MDA) level in newly-hatched chickens. METHODS Fertilized eggs were divided into 7 groups: group T1 as control (without injection), group T2 (in ovo injected with 50 ng/egg ghrelin on day 5), group T3 (in ovo injected with 100 ng/egg ghrelin on day 5), group T4 (in ovo injected with 50 ng/egg ghrelin on day 10), group T5 (in ovo injected with 100 ng/egg ghrelin on day 10), group T6 (in ovo injected with solvent: 1% acetic acid, without ghrelin on day 5) and group T7 (in ovo injected with solvent without ghrelin on day 10). After hatching, serum MDA concentrations were determined. RESULTS Ghrelin administrated groups (T2, T3, T4 and T5) had lower serum MDA level in comparison with control group (T1) or solvent injected groups (T6 and T7). T2 and T3 (ghrelin injection on day 5) had significantly lower MDA concentrations (4.10 and 4.60 nmol/mL, respectively) in comparison with other groups. In T4 and T5, MDA levels were lower than T1, T6 and T7 (non-ghrelin administrated groups) (9.53 and 9.50 in comparison with 10.73, 10.03 and 10.13 nmol/mL) and were higher than T2 and T3. CONCLUSIONS It can be concluded that in ovo administration of ghrelin can have anti-oxidative protection and reduce serum MDA level. Ghrelin administration on day 5 of incubation is more efficient.