The potential of a plant growth-promoting rhizobacterium, Pseudomonas sp. (strain PsJN), to stimulate the growth and enhancement of the resistance of grapevine (Vitis vinifera L.) transplants to gray mould caused by Botrytis cinerea has been investigated. In vitro inoculation of grapevine plantlets induced a significant plant growth promotion which made them more hardy and vigorous when compared to non-inoculated plantlets. This ability increased upon transplanting. When grown together with B. cinerea, the causal agent of gray mould, significant differences of aggressiveness were observed between the inoculated and non-inoculated plants. The presence of bacteria was accompanied by an induction of plant resistance to the pathogen. The beneficial effect from this plant–microbe association is being postulated.