Mastitis of private dairy buffaloes located on different villages of Assiut and Sohag Governorates, Upper Egypt was clinically surveyed and the most common mastitis pathogens were encountered. This survey revealed that 7.12 % of the examined cases were clinically infected and Staphylococcus aureus either alone (58.43 %) or coupled with other pathogens (12.36 %) was the predominant etiologic agent of clinical mastitis. Staphylococcus aureus mastitis (SAM) of dairy buffaloes has various clinical forms: gangrenous, acute, subacute and/or chronic. The later form was more prominent than the gangrenous form, which had seriousness effects on the affected and the neighboring unaffected quarters of the afflicted cases, with severe systemic illness including pyrexia, tachycardia, hyperpnea. Clinical descriptions of the diseased buffaloes with SAM are illustrated and discussed. Epizootiologically, the gangrenous form of SAM occurred in few days post buffalo-calf delivery and usually situated at the base of the teat (annular fold). The prevalence rate of clinical mastitis in multiparous buffaloes was mathematically higher than primiparous animals; however this difference was statistically insignificant (P > 0.05). The prevalence rate of clinical mastitis of the examined animals was primarily increased by increasing the lactation numbers till the third lactation season (peak infection rate, 10.99 %) and thereafter gradually decreased by subsequent increasing in the lactation numbers (range of infection rate, 8.45 % ~ 2.70 %) and dairy buffaloes with more than 9 lactation seasons were found with no signs of clinical mastitis. From an ecological point of view, the prevalence rate of clinical mastitis of private buffaloes located in villages of Assiut and of Sohag Governorates was statistically insignificant (P > 0.05). Bacteriologically, Staphylococcus aureus    (60.58 %), Streptococcus agalactiae (23.08 %) and Escherichia coli (7.69 %) were the predominant frequently isolates and the ratio between them was 8: 3: 1, respectively. However, coagulase negative staphylococci (5.77 %), Streptococcus uberis (1.92 %) and unidentified Gram negative bacteria (0.96 %) were also isolated. A rough questionnaire with the buffaloes' owners was carried out. The questions were turned on the premilking and postmilking sanitary measures, and periodical testing against mastitis and dry-period therapy, and the results were tabulated and discussed.