Twenty-nine populations of five wild annual sunflower species (H. annuus, H. petiolaris, H. argophyllus, H. praecox, H. debilis and H. neglectus) were screened for resistance to Plasmopara halstedii by the whole seed immersion method. Resistant populations were then crossed with cultivated sunflower. Analysis of meiosis and pollen viability in parent and F1 populations was used for characterization of F1 interspecific hybrids, as self-fertilization can also occur. Resistant plants were found in the populations of the species H. annuus and H. argophyllus. The percent of resistant plants in H. annuus populations was 9.09-100% and in H. argophyllus 50.00-57.14%. Irregular chromosome pairing in diakinesis was found in 0-20.83% of meiocytes of the F1 interspecific hybrids, with quadri- and univalents present. Pollen viability of male fertile interspecific hybrid plants was 10.21-98.85% in H. annuus and 39.90-52.47% in H. argophyllus. The obtained results suggest that annual wild sunflower species can be used to obtain resistance, or at least to increase the tolerance of cultivated lines to Plasmopara halstedii.