In this study, synthetic ascorbic acid (100 mg/kg) or different doses of rosehip fruit (5, 10 and 15 g/kg) as a source of ascorbic acid were added to the rations of Nick Brown laying hens grown under cold stress and the effects of these supplements on laying performance, egg quality, egg yolk color values, live weight changes, rectal temperature, feed consumption and feed conversion ratio were investigated. 120 Nick Brown laying hens at the ages of 24 weeks were used and feed and water were provided ad libitum. During the 12 weeks of trial, a photoperiod of 16 hours of light and 8 hours of dark was applied, and the temperature was set at 24°C for 12 hours, 14°C for 12 hours to induce cold stress. It was observed that egg weight, egg white weight and shell weight, as well as feed conversion ratio, decreased in all supplementation groups in comparison to the control group, while yolk weight, Roch color scale and feed conversation ratio increased in all supplementation groups in comparison to the control group, and the egg yolk index, egg white index and Haugh unit values were found to be lower in the group that received 10 g/kg of rosehip fruits supplement than in the other groups. It were determined that in terms of laying performance, weekly number of eggs, egg yield, total egg weight and values of egg yolk and redness were numerically higher in the group that was given 15 g/kg of rosehip fruits in comparison to all other groups, but the supplements did not change the rectal temperature values.