The occurrence of subclinical ovine mastitis among 56 barky breed ewes in part of the North western coastal Desert ,Egypt (Mariout Research station & Bourg El Arab farm) was studied by field tests (bromothymol blue indicator , wpiteeside test, California mastitis test,somatic cell count and catalase test) and also confirmed by the isolation of the causative microbial agents. 32 (28.57%) out of the 112 examined udder halves infected with subclinical mastitis . Out of 112 milk samples, 38 (33.9%) were positive to bromothymol blue indicator, 50 (44.64%) were positive to whiteeside test and 42 (37.5%) were positive to California mastitis test. whiteeside test & California mastitis test scores of 2+ ve & 3 + ve were positively correlated with the results of microbial culture. Staphy|oylococcus aureus, Streptococcus ePidermidiis, Streptococcus agalactia, Escherichia Coli, Corynebacterium spp., Penicllium spp., Aspergillus flavus, Aspergillus fumigatus and Aspergillus terreus could be isolated from such cases with incidence of 30%, 16%, 20%, 12%, 4%, 6%, 4%,4% and 4% respectively. The in vitro sensitivity pattern of isolated organisms was tested against different antibiotic and antimycotic discs and the obtained data were presented. Control measures for improvement of the hygiene quality of ewe's milk were suggested.