Heat stress remains the most important stressor, especially across the tropical regions of the world. In the current study, effects of ascorbic acid were investigated for its impact on summer-induced heat-stress in ducks. A total of 60 twelve weeks old White Pekin ducks were randomly distributed into 3 experimental groups with replicates having 10 birds in each group. The ducks under the therapeutic trial groups were supplemented with vitamin C of 250mg or 500 mg per kg of feed along with a basal diet. This experimental feeding, ad libitum, continued for 7 weeks period. The maximum and minimum temperature along with relative humidity in the pen was recorded on daily basis, throughout the experiment. Blood samples were collected and analyzed for haemato-biochemical and oxidative stress parameters. Vitamin C treatment improved the haemato-biochemical and oxidative parameters alteration caused by summer-induced heat stress in ducks. Therefore, dietary supplementation by vitamin C have significant role in mitigating the summer-induced heat-stress.