This study was performed during winter 2002 in a sheep flock manifesting respiratory embarrassments in 44 out of 321 animals of different ages and sex. Bacteriological examination of nasopharyngeal swabs taken from diseased sheep revealed the detection of Haemophilus somnus (H.somnus) either alone (55.6%) or in combination with Streptococcus pneumoniae (22.2%), Klebsiella pneumoniae (11.1%), and Staphylococcus aureus (11.1%). Also H.somnus was detected from the nasopharyngeal swabs collected from in contact apparently healthy cattle. Electrophoretic pattern of Haemophilus somnus isolated from diseased sheep and incontact clinically normal cattle proved the similarity of ovine and bovine strains, such criteria have potential value for epidemiological studies of haemophilosis among farm animals. Clinical signs exhibited on the diseased animals were described and some epidemiological data and the treatment of diseased animals were studied and discussed. Finally, the main points recommended in control of ovine haemophilosis were detection and treatment of diseased animals after application of sensitivity test, careful management to reduce the influence of predisposing factors, interspecies transmission of haemophilus somnus or contact of sheep with cattle or other reservoirs should be avoided and vaccination of sheep against Haemophilus somnus (local strain) either alone or in combination with other bacterial or viral vaccines used in Egypt.