The aim of this study was to determine and investigate the slime production of Coagulase negative staphylococci (CoNS) isolates by phenotypic method on Congo Red Agar plates (CRA) and Genotypic detection of icaA, icaD and mecA genes by polymerase chain reaction (PCR). The study was done on 105 milk samples obtained from bovine clinical mastitis and found that 101samples (96.2%) were positive for bacterial culture. CoNS species can be isolated from20 samples with a percentage 19.8%. Their ability to form biofilm as one of the most important virulence factors using Congo Red Agar (CRA) method was investigated, in which 13 out of 17 CoNS isolates (76.47%) were found to be slime producers. By PCR, mecA gene was found in threeout 6 CoNS isolates (50%). Also, six (100%) and three (50%) isolates were positive for icaA gene and icaD gene, respectively, and 3 isolates (50%) were positive for both icaA and icaD genes. In addition, one out of the six CoNS isolates (16.67%) was positive for the presence of icaA, icaD and mecA genes and also it has the ability to form biofilm. Conclusion, findings of the present study demonstrated the ability of CoNS isolated from bovine clinical mastitis to form biofilms. This must be considered as an alarming situation, and so attention must be paid toward implementation of new ways for effective prophylaxis, control, and treatment of such infections in the dairy farms. The prudent use of antibiotics and rapid and continuous screening for resistant microorganisms should be more focused to prevent the emergence and spread methicillin resistant coagulase negative staphylococci, because these strains can cause severe damage to infected sites and may be widespread in the environment.