The effect of Phytophthora parasitica Dast var. nicotianae (Breda de Haan) Tucker (Ppn) race 0 culture filtrate (CF) on direct organogenesis of tobacco stem explants was evaluated using five tobacco haploid lines, which were selected based on their field reaction to Ppn (race 0). The culture filtrate used in different concentrations in MS medium suppressed bud formation from stem explants of susceptible tobacco cultivars more than those from resistant tobacco cultivars. The lowest concentration of CF (2%) stimulated bud formation in tobacco stem explants from both susceptible and resistant cultivars compared to the controls without CF. Ten percent CF is suitable for srceening in vitro Ppn resistance of tobacco cultivars at stem explants level. The slection scheme for resistance to Ppn CF and for increased resistance to Ppn was established.