The Powdery mildew (Erysiphe cichoracearum) resistant variety of Oriental tobacco Pobeda 3 was developped in Bulgaria. The purpose of this investigation was to produce isogenic lines with oriental variety Harmanlikska basma 163 which is sensitive to this disease. The inheritance of powdery mildew resistance of hybrids BC1, BC2, PC3, BC4, BC5, BC6 and the F1-F5 hybrids obtained by crossing Pobeda 3 with Harmaliska basma was studied. In F5, isogenic lines resistant to powdery mildew were obtained which had a dominant gene obtained from the variety Pobeda 3 (N. debneyi).