Abstract: The study detected various kinds of pathogens in pigs suffering from respiratory syndrome by PCR technique and immunofluorescent test. The RT-PCR results showed that the tissue samples of lung and lymph nodes from diseased pigs were positive for PRRSV variant but negative for PRV,CSFV,PCV2 or SIV. A virus strains were also isolated from positive samples by inoculating it onto Marc-145. The 30 days-old piglets inoculated with the isolates showed the same symptoms as appeared naturally on the diseased pigs in the clinic. The virus was recovered from and the interstitial Pneumonia observed in the diseased pigs. Thus,it was concluded that the respiratory disease outbreak in the swine farm was caused by a PRRSV variant.