The aim of the present study was to determine a relationship between the somatic cell count in milk and daily yield, chemical content as well milk technological usefulness in different breeds cows. The examinations included a total of 1867 milk samples collected from cows of four breeds: Polish Holstein-Friesian, Black-White variety--712 and Red-White variety--356, Simental--587 and Whitebacks--212 samples. Each sample was examined to determine somatic cells count (SCC), basic chemical composition, thermostability and rennet milk coagulation time. Based on the SCC score, within each cow breed, the milk samples were classified into one of four groups, i.e., I--up to 200,000 cells/ml, II--200,001-400,000 cells/ml, III--400,001-1,000,000 cells/ml and IV above 1,000,000 cells/ml. The increase in SCC was associated with the reduction in daily milk yield of the high-yielding dairy cows. As far as milk composition is concerned, an increased SCC level was connected with raise in a total crude protein content and a distinct reduction in lactose level (P < or = 0.01) as well as with a small (P < or = 0.05) increase in fat and casein content, and elevation in protein to fat ratio. The time of milk enzymatic coagulation also was lengthened (P < or = 0.01) but it did not influence its thermostability. The significant relationship (breed x SCC) for the protein, casein and lactose content, protein to fat ratio as well as rennet milk coagulation time has been revealed.