Gray mold caused byBotrytis cinereacauses significant losses in tomato crops.B. cinereainfection may be halted by volatile organic compounds (VOCs), which may exhibit fungistatic activity or enhance the defense responses of plants against the pathogen. The enhanced VOC generation was observed in tomato (Solanum lycopersicumL.), with the soil-applied biocontrol agentTrichoderma virens(106spores/1 g soil), which decreased the gray mold disease index in plant leaves at 72 hpi withB. cinereasuspension (1 × 106spores/mL). The tomato leaves were found to emit 100 VOCs, annotated and putatively annotated, assigned to six classes by the headspace GCxGC TOF-MS method. InTrichoderma-treated plants with a decreased grey mold disease index, the increased emission or appearance of 2-hexenal, (2E,4E)-2,4-hexadienal, 2-hexyn-1-ol, 3,6,6-trimethyl-2-cyclohexen-1-one, 1-octen-3-ol, 1,5-octadien-3-ol, 2-octenal, octanal, 2-penten-1-ol, (Z)-6-nonenal, prenol, and acetophenone, and 2-hydroxyacetophenone, β-phellandrene, β-myrcene, 2-carene, δ-elemene, and isocaryophyllene, and β-ionone, 2-methyltetrahydrofuran, and 2-ethyl-, and 2-pentylfuran, ethyl, butyl, and hexyl acetate were most noticeable. This is the first report of the VOCs that were released by tomato plants treated withTrichoderma, which may be used in practice againstB. cinerea, although this requires further analysis, including the complete identification of VOCs and determination of their potential as agents that are capable of the direct and indirect control of pathogens.