A total of 150 lung samples (50 normal and 100 pneumonic) were collec ted from slaughtered sheep at Cairo abattoir and examined for the presence of pasteurellae. The incidence of pasteurellae among pneumonic and normal lungs were 23% and 6% respectively. Pasteurella multocida was recovered from 10% of pneumonic lungs, while Pasteurella haemol itica was isolated from only 20% of pneumonic lungs. Five sheep were artificially infected by the isolated strains of P.multo cida and were slaughtered after a therapeutic treatment. Significant differences were reported in living body weight, dressing-out percentage, the weight of the internal organs, fatty tissue, meat cuts grade 1 and III. Moreover, the chemical composition and the over eating quality test revealed also a considerable variation between the artificially in fected and the controlled groups.