Newcastle disease virus (NDV) was isolated and identified for the first time from a flock of Japanese quail suspected to ND in Iran. Birds of the flock aged variously, and some of them died from the disease. Loss of appetite, weakness and decrease in egg production, diarrhea and nervous symptoms were the main clinical signs in the birds. Hemorrhagic lesions of the intestinal tracts and proventriculus were found in gross pathology investigations. Samples were taken for bacteriology, parasitology and virology. The results of parasitology and bacteriology examinations were negative. The virus was isolated only from brain samples and was identified as Avian Paramyxovirus type 1 (APMV-1) by HI test using NDV-Specific antibody. The pathogenicity of the virus was identified by mean death time (MDT) in embryonated chicken eggs, intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index (IVPI) in chickens. Values 40, 1.62 and 2.31 were obtained for MDT, ICPI and IVPI respectively. These results indicate that isolated APMV-1 belongs to NDV velogenic strains with severe pathogenicity. According to these findings vaccination against NDV in quail farms of Iran is highly recommended.