The characteristic of milk productivity of cows of Holstein and Simmental breeds in LLC “Sibirskaya Niva” in the Maslyaninsky district in the Novosibirsk region has been given. It has been revealed that under the natural and climatic environments of the Western Siberia, when creating favorable conditions for feeding and housing for cows of Holstein and Simmental breeds have sufficiently high milk productivity. It has been found that Holstein first-calf heifers surpassed their Simmental herdmates by 959 kg in milk yield for the first 305 days of lactation under the same conditions of housing and feeding, by 3,1 kg in daily milk yield, by 38,2 kg in milk fat yield, and by 28,3 kg in milk protein yield (P < 0,001). There were no statistically significant differences between animals of Holstein and Simmental breeds in terms of fat and protein content in milk, which amounted to 3,94 and 2,96 % in Holstein breed and 3,97 and 2,98 % in Simmental breed, respectively. Both breeds have shown high milk productivity during the first 3 lactations. Thus, the milk yield of Holstein cows for the first 3 lactation was 6475–9290 kg, Simmental cows it was 5516–7680 kg, fat content was 3,93–3,99 and 3,96–3,97 %, respectively. The protein content in the milk of cows of both breeds did not exceed 3,0 %. High variability has been found in milk yield, yield of milk fat and protein, the coefficient of milk content and duration of lactation, the lowest in the content of protein and fat in milk and live weight. The correlation coefficients between the fat and protein content in milk were generally positive, but did not exceed 0,28. Therefore, breeding in the herd of cows in LLC “Sibirskaya Niva” have to be conducted not only by fat content, but also by protein content in milk.