An intra venous injection or 1.1'. + intra tracheal injcction in swine might kill the animal when the amount of microorganisms is large. The disease is septicemic without any pulmonary localization. To " fix " Pasteazvella inside the lungs they should be damaged previously. P. Ull iltocida is well known as an " opportunist " invading the breached tissues. Therefore, we choosed the administration of embryonated Ascari.s suzinr eggs to 8 days before the trial. Ascaris + Pasteurella gi 1' cn by uzebulisatioza : (particle size I to 3 [1) the characteristics of the disease were : severe respiratory svmptoms with high hvperthermia,-polyarthritis (the septicemic facet of Pasteurella),-a loss in weight and an acute broncho pneumonia with an average death time of 5 days. Ascavis-+-Pasteaevella given by intra tracheal (and 1. 1'.) route: the same disease was obtained, but without polyarthritis. The acute broncho pneumonia was severe and death occurred 4 to 8 days after and was dose-related. Emphasis must be laid on the difficulty of reproducing in the laboratory a disease so commonly found in the field, as the purpose was to ol>tain a regular course and not a too early mortality.