The quality of milk is affected by many factors - health status of cows, milk handling and hygiene of milking. The cows being bred in Estonia are suitable for local conditions due their high milk performance and relatively good fattening and meat qualities. The data about ten-month milk yield, fat and protein content, fat and protein yield and somatic cell count of the milk of the daughters of each bull were collected. Cow's sire, enterprise, birth-year, lactation, milking equipment and milking operator were fixed in data-base. All the analysed factors affected the milk somatic cell count. Most essential of them were agricultural enterprise, milker and over-milking (P0.001).