Induced resistance of tobacco to brown spot, black lowering ( Colletotrichum sp.), black shank, wildfire, and TMV was tested in a greenhouse and in field plots where the inducers were the hypovirulent strain TBA16 of Alternaria alternata , non-pathogenic Pseudomonas fluorescens P1, the hypovirulent strain N14 of ToMV, chemical ID1, and SRS2 (a preparation with resistance inductory function). Induced resistance of between 41% and 89% to brown spot, black shank and black lowering was achieved with the strain TBA16, from which the cell wall components of spores were taken as the functional element for the SRS2 preparation. SRS2 gave 60% resistance induction in the greenhouse and 75% protection of tobacco from brown spot in the field, but showed no role in inducing resistance to the other four diseases. Induced resistance of 28-87% to brown spot and wildfire was acquired with the bacterium P1, which had no effect on the other three diseases. Resistance of 28-87% to all five diseases was induced by both N14 and ID1. Practical approaches are suggested for utilizing the inducers to control tobacco diseases.