Abstract: We investigated the heterogeneity of the ribosomal internal transcribed spacer 2 (ITS2) within 131 individuals of Phlebotomus papatasi from 25 geographic localities in 10 countries by sequencing the PCR-amplified copies of this spacer. Sequence heterogeneity was observed in both sexes from all localities. There are many microsatellite sequences that show insertion-deletion polymorphisms. The length of the ITS2 ranged from 340 to 512 bp and the average GC content of the ITS2 was 29.2%. The phylogenetic relationships among the members of P. papatasi were inferred by neighbour-joining analysis. Although the relationships among P. papatasi populations could not be completely resolved, the phylogenies were in good agreement with previous enzyme electrophoresis studies.