A total of 173 quarter milk samples collected from 297 dairy cows and 178 buffaloes belonging to housed bovine animals of the farmers in some villages of Ismailia- Governorate, was subjected to C.M.T. to determine the subclinical mastitic cases. The incidence of subclinical mastitis was 22.2% in cows and 14.6% in buffaloes. The occurrence of subclinical mastitis, as related to the age of animals, showed that the incidence was increased with advancing age. Most of subclinical mastitic cases were recorded in one or two quarters. Bacterial examination of the milk samples revealed various pathogens. Staph.. aureus was the prevalent microorganism in dairy cows, while, in dairy buffaloes, Escherichia coli was the predominant organism.