This research was conducted to determine the characteristics of milk yield of Holstein Friesian cows raised at Kocas state farm in Central Anatolia. The material of the research was 970 lactation records of 362 dairy cows raised from 1988 to 1995 at Kocas state farm. Statistical analysis of the records was conducted with the Minitab version 9.2 computer program. Significant differences between groups were determined by the method of Least Significant Difference (LSD). The general mean values of lactation length, lactation milk yield and 305 day milk yield were respectively 304.4±1.39 days, 4966±32.96 kg and 4784±27.35.