Spore attachment of three Pasteuria penetrans isolates was assessed on juveniles of Meloidogyne incognita and Meloidogyne javanica populations from Greece. The nematode populations differed in their ability to reproduce on tomatoes with the Mi gene, conferring resistance to rootknot nematodes. The numbers of attached spores did not discriminate virulent from avirulent populations within each species. The differences in attachment rates probably reflect the specificity of Pasteuria penetrans to different Meloidogyne populations of the same species, within a country or even the same area.