The samples were collected from 25 uteri of 20 non-pregnant (14 cattle and 6 buffaloes) and 5 pregnant (2 cattle and 3 buffaloes) and 25 supramammary lymph nodes (16 cattle and 9 buffaloes). From abattoirs in El-Menofia governorate, were previously proved to be seropositive. In addition to 6 samples (2 lungs, 2 livers, 2 intestines) were collected from two aborted fetus from Brucella seropositive cattle, from Faculty of Veterinary Medicine Farm , Benha university. Brucella melitensis was isolated from supra-mammary lymph nodes. B. melitensis was detected in 20 samples (15/16 cattle and 5/9 buffaloes) and B. abortus was detected in one sample (pregnant buffalo) by Bruce-ladder PCR and whole-genome sequencing. Pathologically, the examined non-pregnant uteri of cattle and buffaloes had severe degenerative changes in the uterine mucosa which represented by ulcerative endometritis, in addition to fibrosis that was confirmed by Masson's trichrome stain. Focal coagulative necrosis was detected in pregnant cattle uteri and uterine caruncles. Ulceration in the uterine mucosa with mucoid degeneration, and vasculitis were recorded in the uterus of pregnant buffaloes. Meanwhile, Lungs of fetus have fibrinous pneumonia, extensive degenerative changes were detected in the liver and intestine of fetus. Finally, it was concluded that natural infection with brucellosis causing variable lesions in different organs either in pregnant or non-pregnant animals.