Fourteen avian paramyxovirus type 1 (APMV-1; Newcastle disease) viruses isolated from dead free-living and domestic pigeons in Slovenia between 2000 and 2008 were analyzed by a molecular characterization of a part of the fusion protein gene, which included the region encoding the fusion protein cleavage site. Phylogenetic analysis indicated that the Slovene pigeon paramyxovirus type 1 (PPMV-1) viruses do not cluster together but instead are divided into two groups—4bi and 4bii—of sublineage 4b. Nine Slovenian strains were placed in group 4bii. Five other strains clustered together with PPMV-1 from group 4bi. The sequence of the fusion protein cleavage site of all Slovenian strains was typical for pathogenic APMV-1. The ¹¹²RRQKRF¹¹⁷ motif was present in the strains from group 4bii, whereas strains from group 4bi displayed the ¹¹²GRQKRF¹¹⁷ motif.