Nutrient administration in-ovo could be considered as an alternative method to improve hatchability and duckling weights followed by better economic performance. On the 12th day of incubation, fertile duck eggs (n= 500) were distributed into 5 groups: uninjected control; 0.1 ml corn oil; 0.1 ml corn oil plus 10 mg vitamin E; 0.1 ml saline; and 0.1 ml saline plus 3 mg ascorbic acid. In-ovo injection of vitamin E but not ascorbic acid resulted in higher hatchability percentage compared to the uninjected control; however this was not statistically confirmed. In-ovo injection of either vitamin E or ascorbic acid resulted in significantly (P < 0.05) higher body weights at hatch, final body weights, and feed intakes than the uninjected control group. However, both male and female ducklings hatched from eggs injected with either vitamin E or ascorbic acid had better feed conversion during the starting period only. The carcass characteristics and relative lymphoid organ weights did not differ (P < 0.05) between the in ovo injected groups and the uninjected controls. In-ovo injection of either vitamin E or ascorbic acid resulted in significant increase (P < 0.05) in the geometric mean of the 1st antibodies titers of males and the 1st and 2nd antibodies titers of females compared to the uninjected control. It could be concluded that in-ovo injection of vitamin E and ascorbic acid improve the embryonic and post-hatch growth of Muscovy ducks.