Forty samples (liver, spleen and intestine) from freshly dead quails and ninty five samples (liver, spleen and intestine) from freshly dead chikens (1-18 month age) were collected from different farms of Assiut governorate. Cl.colinum was isolated from quails and chickens at a rate of 70% and 27.4% respectively. Experimental infection of 5- week old quails intramuscular with isolated Cl.colinum from chickens revealed 100% mortality within 2-4 days postinoculation while 100% mortality within 8 days postinoculation was reported in orally infected quails. Intramuscular experimental infection of 12-day old chickens with isolated Cl.colinum caused 70% mortality within 48h. postinoculation. Reisolation of Cl.colinum from inoculated quails and chickens was successful. Histopathological study revealed that the intestine and liver were the most organs affected in chickens and quail infected. The intestine revealed epithelial necrosis desquamation, ulcerations and inflammatory cell infiltrations. The liver showed fatty degeneration, hepatocytic necrosis with moderate inflammatory cell infiltrations.  Changes in glandular stomach were additionally reported in some infected chickens and myocardial necrosis was observed in one infected chicken. In vitro sensitivity test showed that gentamycin, ampicillin and naladixic acid were the most effective drugs.