Fifty five milk samples were collected from dairy Friesian cows suffering from clinical mastitis in a farm at Quena Governorate. The samples were subjected to microbiological examination .The main isolated pathogenic bacteria were identified biochemically as Escherichia coli (36.3%), Staphylococcus aureus (23.6%) Streptococcus agalactiae (18.2%), Klebsiella pneumoniae (12.7%) and bacterial free samples (9.1%) . Sensitivity tests for the bacterial isolates revealed that the tested strains were sensitive to ciprofloxacin, nortril, gentamicin and lincospectin