An evaluation of the disease causing potential of Sclerotium rolfsii on some tomato cultivars in bioassay was conducted. The cultivars showed disease symptoms such as chlorosis, wilting, damping off, blighting and necrosis. For Shase, Hoozua and UTC cultivars, chlorosis wilting and damping off ranged from 50 –100% in week three while blighting and necrosis was 0%. In week four, chlorosis, wilting and damping off was 100% while blighting and necrosis was 0%. In week five and six, disease symptoms were 100% on all cultivars. Analysis of Variance (ANOVA) revealed significant differences (P < 0.05) in the response of the different cultivars to Sclerotium rolfsii infection with respect to their controls. Severity of Sclerotium rolfsii infection on the tomato cultivars ranged from 1-5 which indicated 1-100% of plant tissue damage. There was no significant difference (P > 0.05) in the severity of Sclerotium rolfsii infection on the tomato cultivars in each week. Sclerotium rolfsii proved to be highly pathogenic on the evaluated cultivars of tomato in pot experiments.