Milk from 4,917 dairy cows of the Bohemian Spotted and Black Pied cattle in the 1st to 11th lactations was individually sampled on a Fossmatic apparatus and the somatic cell count was measured. The effects of the cowshed, month of the year, sequence of lactation, stage of lactation and of the father were evaluated using model equations of multi-factorial analysis according to HARVEY. The effects of housing, the sequence and the stage of lactation on the somatic cell count were found to be significant. The effect of the month of the year was insignificant. The effect of the father on the somatic cell count in the milk was not substantial. The heritability coefficient was h² = 0.033-0.044.