· Total number of 799 sheep, 892 goats, 86 cattle and 68 camels suffering from respiratory tract affections constituted the material for this analy tical study which covered the 4 seasons of the year, 1987. Clinical examinations were carried out in the Veterinary Teaching Hospital and in some farms at Al Hasa, Eastern Province of Saudi Arabia.
Rresults revealed that. Pasteurella spp. were the main causative agent in the majority of cases. However, other causes which may include viruses, mycoplasma, Klebsiella, chlamydia and others may have been responsible for the different types of pneumonia and pneumoenteritis observed in this region but could not be isolated under routine and field conditions which dominated this investigation. Further studies, therefore, appear neces sary. A higher incidence of infection was observed during winter time and also during stormy months (March/April) possibly associated with an environmental stress factors during these months. Other variations in incidence in relation to different age group < strong>s and animal sp < /strong>ecies are presented and discussed.