The Newcastle disease is one of the most important avian viral diseases that infect many species of birds such as chickens and pigeons. Virulent strain of Newcastle disease virus that is the causative agent of this disease in pigeons called pigeon paramyxovirus-1 (PPMV-1) and also cause virulent Newcastle disease in chickens. In order to isolate and clone the F gene cleavage site of PPMV-1, cloacal and oro-tracheal swabs samples were collected from 50 pigeon lofts in Ahvaz during 2013-2014. Also samples of brain, trachea, lungs, liver, spleen and cecal tonsils from the suspected  died birds were collected. Each sample after preparation was inoculated to 9 to 11-day-old embryonated eggs and after collection of alantoic fluid, hemagglutination inhibition test was performed by specific positive PPMV-1 serum. Then, virus RNA of sample was extracted and cDNA synthesized. Primer sequences were used to amplify a 535 base pair fragment in polymerase chain reaction (PCR). Finally, PCR products were analyzed by electrophoresis. Results of the present study indicated that 9 of 50 pigeon lofts were positive in embryonated egg and in rapid hemagglutination test. hemagglutination inhibition test with specific PPMV-1 positive serum confirmed that all of isolated viruses are PPMV-1. Eighteen Percent of the suspected pigeons were positive to PPMV-1.  PCR, confirmed that all 9 lofts were positive and  PCR products of samples indicated 535–base pair fragment in electrophoresis. It was concluded  that PPMV-1 was enzootic in pigeon lofts of Ahvaz and could always be a threat for poultry industry. Thus, sequencing and determining the cleavage site of virus; quarantining, eliminating and effective vaccination of infective pigeons and evaluating virulent of these viruses in poultry industry are very important in prevention, control and circulating virus from pigeons to chickens and  vice versa.