Stem rot and target spot, caused by Rhizoctonia solani and its teleomorph Thanatephorus cucumeris, respectively, can cause serious problems in greenhouse production of tobacco seedlings. No fungicides are currently registered for control of these diseases, and previous screens for genetic resistance in tobacco have been limited. The objective of this study was to screen 99 accessions comprising several classes of tobacco cultivars and related Nicotiana species for resistance to a stem rot (AG-4) and a target spot isolate (AG-3) of R. solani. Tobacco seedlings were grown in polystyrene trays floating on a nutrient solution in growth chambers to replicate greenhouse growth conditions. Rice grains infested with stem rot and target spot pathogens were placed on the trays to infect the plants. Significant differences in disease incidence were observed among the accessions for both stem rot and target spot. Disease incidence ranged from 12.5 to 100% for stem rot and 6.2 to 97.9% for target spot. This wide range of disease incidence observed among accessions for both diseases indicates that several accessions may have useful levels of partial resistance and may be suitable for use in future breeding efforts. Many burley cultivars had low levels of target spot, and tobacco introductions TI 1311 and TI 1316 had resistance to stem rot. The resistance in TI 1311 is inherited and appears to be dominant.