Chemical and electrophoretic properties of raw milk samples with different somatic cell counts (SCCs)(<200 000, 200 000-800 000 and >800 000 cells ⁄ mL) were determined. Milk was analysed for fat, lactose, total nitrogen (TN), non-casein nitrogen (NCN), ratio of casein nitrogen to total nitrogen (CN ⁄ TN), pH, titratable acidity (TA), solid-non-fat (SNF), total solid (TS), the amount of a s -casein and bcasein. Milk SCC had no significant effect (P ‡ 0.05) on fat and TN. An increase in the SCC resulted in an increase in pH and NCN content, and a significant decrease in lactose, TA, SNF, CN ⁄ TN, a s -casein and b-casein. Milk quality of Holstein dairy cattle deteriorate due to higher proteolytic activity associated with high SCC.