Wildfire (Pseudomonas syringae pv. tabaci, races 0 and 1) and angular leaf spot (P. syringae pv. tabaci, ALS form) are major diseases of tobacco in Zimbabwe. A breeding programme designed to develop commercially acceptable mammoth (non flowering) lines resistant to both races of wildfire and angular leaf spot was started in 1988. A cross of the resistant standard line, WZ 2-3-1-1, to Kutsaga Mammoth 10 was made. This cross is of particular value as it incorporates the gene for resistance to wildfire race 0 from Nicotiana longiflora in Kutsaga Mammoth 10 with the genes for resistance to wildfire races 0 and 1 and angular leaf spot from N. rustica in the WZ line. Both parents produce good quality cured leaf. From this cross the resulting F1 hybrid was then back-crossed to Kutsaga Mammoth 10. From the segregating B1 material, mammoth type plants resistant to wildfire race 1 and angular leaf spot were selected and back-crossed again to Kutsaga Mammoth 10. By continuous inoculating, and selecting and back-crossing the breeding material was continued to the B3 generation, then individual selections were both back-crossed and selfed. The B4 and B3S1 generation selections were then selfed and at the same time tested for agronomic qualities. From the results obtained, all B4 and B3S1 lines performed better than the Kutsaga Mammoth 10 (control). All lines had acceptable nicotine and sugar levels. True breeding lines are expected in B4S1 and B3S2 generations.