Herein, the effect of rosehip marmalade addition to kefir on it antioxidant activities was investigated. Firstly, the production of kefir, having the supplements of semi-skimmed milk, powder kefir ferment, and rosehip marmalade at different proportions (0% (control), 10%, and 15%) was made. Kefirs were stored in the refrigerator on days 1, 7, 14 and 21 at 4 ± 1ºC. It has been determined that it has a highly significant (p<0.01) effect on TPC during the storage period. In addition, it has been determined that storage period has a significant (p<0.05) effect on Vitamin C, while has a insignificant (p>0.05) effect on DPPH. The rosehip marmalade kefirs and control kefirs vitamin C and total phenolic content values were in the range of 7.85-9.04 mg 100g-1 and 1931, 18-2447,11 mg GAE L-1, respectively. On the other hand, the 2.2-diphenyl-1-picrylhydrazyl values of the samples were determined up to 67.85 μg ml-1 (EC50). With this research, it was concluded that the low Vitamin C content of kefir, which stands out in dairy products especially with its probiotic character, can be increased and it can be transformed into a fermented product with different sensory characteristics, both probiotic and prebiotic. [ABSTRACT FROM AUTHOR]