From a total of 85 Holstein Fresian cows which were subjected to subclinical mastitis using modified white test (MWT) and California mastitis test (CMT), 260 quarter milk samples showed 244 (93.8%) and 124 (47.7%) positive results respectively. 85 individual cow milk samples were subjected to MWT, CMT and somatic cell count (SCC) rather than bacteriological isolation and count.  it is concluded that 87, 67 and 73% were positive results. test Sensitivity determination indicated that MWT, CMT and SCC showed 86.1%, 64.6% and 74.7% sensitivity. While their agreement with major pathogens isolation were 80, 60 and 72.9%, respectively. Major mastitis pathogens (Streptococcus spp., Coliforms, bacillus cereus, Pseudomonas aurogenosa and Staph aureus) showed prevalences of 64, 47, 33, 17 and 10%, respectively. Minor mastitis pathogens (Staph coagulase-ve, mold and yeast) showed 66, 59 and 57, respectively. SCC was the only screening test that correlated significantly (P>0.05) with the total bacterial count (TBC). CMT showed highly significant correlation coefficient (P>0.001) with each of MWT & SCC. The study recommended usage of more than an indirect screening tests to detect subclinical mastitis specially MWT and SCC. Moreover, periodical examination for TBC was essential either for herd health or milk hygiene and consumption.