Background: Human milk contains the nutrients necessary for the growth and development of babies as it contains essential bioactive components to support the immune system. Galactooligosaccharides which are important indigestible prebiotics, help multiply the growth of beneficial microorganisms selectively and inhibit the growth of the pathogenic organism. The nutrition of the mother is essential since it affects the composition of mother’s milk. Kefir affects the digestive system, lactose intolerance immune system, anti-microbial effects, probiotic and prebiotic features. However, there is no report on how kefir consumption may have effects on composition of mother’s milk. In this aspect, this study aimed to determine the effects of kefir consumption on the carbohydrate profiles of the mother’s milk. Methods: This study started immediately after birth, mothers were fed with 500 ml/day of kefir made from kefir grains for 30 days in the KF group. Mothers who are in the control group (KI) continued their regular diet. Mother’s milk was collected on the 10th, 20th, and 30th day and stored at 4ºC. Carbohydrate profile including GOS was determined using the liquid chromatographic method with the HI-PLEX column.Results: The mean lactose concentrations of mother’s milk who consumed kefir were 4,68; 4,72; 5,89 g/100ml on days 10th, 20th, and 30th, respectively. Glucose concentrations were 0,29; 0,08; 0,21 g/100ml on 10th, 20th, 30th days, respectively. For the mother’s milk samples in the control group, the averages of lactose concentration were 5,42; 5,73; 5,51 g/100ml on days 10th, 20th, and 30th. GOS peaks were specified depending on the rich content of prebiotics. Conclusion: Consumption of authentic kefir may have effect on carbohydrate profile, including GOS of mother’s milk. Keywords: Human milk, kefir, prebiotic, galactooligosaccharides