Fifty five wild Nicotiana species, five autotetraploid forms and twenty nine botanical varieties were tested for resistance to Thielaviopsis basicola (Berk. and Broome) Ferr. The study was conducted in the greenhouse, using floated styrofoam trays. The plants were grown in a peat medium artificially infected with spores of the fungus and in control medium. The level of infection and fresh roots weight of each entry were determined. The resistance varied with the species and forms. N. debneyi was found to be most resistant to black root rot, without any disease symptoms. N. glauca, four botanical varieties of N. rustica, N. corymbosa, N. occidentalis and N. amplexicaulis are also high of the resistance. They can be used in interspecific hybridization for developing initial breeding material resistant to black root rot. N. umbratica, N. noctiflora, N. petunioides, N. megalosiphon, N. otophora, N. glutinosa, N. ingulba and N. sylvestris showed high level of susceptibility. The root systems of highly susceptible species were completely damaged.