Abstract: Mastitis is an inflammation of the mammary gland with local and or symptoms that occasionally result in a systemic infection. This disease has a profound impact on animal welfare and milk quality. The aim of this research was to investigate the microbial etiology and the occurrence of antimicrobial resistance. Moreover, difference between staphylococci antimicrobial resistance isolated subcliniques cases and clinical cases was investigated. In total, 213 quarter milk samples were collected from 56 dairy cows at 6 farms from February 2011 to February 2012. The quarter milk samples were bacteriological analyzed and scored using California Mastitis test. The most frequently isolated bacteria were the enterobacteriacea, staphylococci and streptococci, the presence of resistance was evaluated in all specific udder pathogens. Staphylococci antimicrobial resistance was performed by detection of mecA gene and the Pantin Valentine leukocidin coding gene (pvl) by PCR. The most common isolated of 250 bacteriological diagnoses were Enterobacteria (45.76%) Staphylococcus aureus (38.9%), coagulase-negative staphylococci (2.7%) and Streptococcus (12.43%) in milk samples from clinical cases (47.87%) and subclinical cases (52.12%) infected cows. All retained Staphylococcus aureus species contained gyr gene. Overall the S. aureus isolates were sensible to antimicrobials compounds. Staphylococcus, Escherichia coli and Enterobacter cloacae were the most frequently isolated pathogens. The testing of Staphylococcus antimicrobial resistance isolated subclinical and clinical cases showed the absence of resistance to antimicrobials agent.