RK 3, a male-sterile hybrid of Speight G28 and STNCB 2-28, has been used for some years as the best Granville wilt resistant cultivar available in Zimbabwe. However, it has not withstood the increased infection pressure of recent years. Twenty six S8 BAG lines derived from the fertile equivalent of RK 3 were tested for Granville wilt resistance, with three controls, the two parents and one breeding line. They were planted into a field in which RK 3 had been severely infected the previous season. The level of resistance was high in Speight G28 and moderate to low in STNCB 2-28. However, the most susceptible line was as severely infected as the control Hicks, while the most resistant was less infected than Speight G28. It is postulated that the genes from Speight G28 and STNCB 2-28 are different, with no common loci. STNCB 2-28 was bred from TB 22 (a breeding line with dominant powdery mildew resistance from Nicotiana tomentosiformis ), the American cultivar NC 89 and ST (a breeding line with resistance to Meloidogyne javanica derived from the American cultivar SC 72 and a primitive N. tabacum). The ST line had a moderate to high level of resistance, and it is possible that the source of resistance in STNCB 2-28 came from this line.