This study surveyed the mastitis prevalence and risk factors in buffalo's population in Dakahlia Governorate. A total of 471 Water buffaloes (Bubalus bubalis) brought to the Veterinary Teaching Hospital, Mansoura, Dakahlia Governorates from 2009 to 2012 were analyzed to determine, the seasonal occurrence of mastitis, prevalence in relation to the lactation stage. Isolation and identification of causative agent using PCR and other serological technique were applied. The prevalence of buffalo's mastitis was 19.9% and 5.9% for clinical and subclinical mastitis respectively. A high incidence of clinical mastitis (51.6%) was observed in animal during their early lactation stage, while high incidences of subclinical mastitis recorded (12.9%) in late lactation stage. And the most isolated microorganism is E-coli spp. The Statistical analysis of our results revealed that a significant variance between the occurrence of mastitis and lactation season,      P< 0.001.