Tropospheric ozone (O₃) has long been documented to cause an injury to plants, but a plants’ protectant, widely applicable in agronomical practice, does not exist. We evaluated the potential antiozonate efficacy of the antitranspirant di-1-p-menthene (Vapor Gard) compared with ethylenediurea (EDU) on Bel-W3 tobacco plants. Plants were treated either with water, or by EDU (10, 100, and 500 mg dm⁻³), or by vapor (1, 5, 10, and 50 ml dm⁻³) and were exposed either to O₃-enriched (90 ppb) or O₃-free air, for 12 days and 8 h day⁻¹. EDU when applied at 10 mg dm⁻³ did not protect the plants against O₃, but when applied at 100 and 500 mg dm⁻³ offered a significant protection to the plants. Vapor, when applied at 1 ml dm⁻³ did not protect the plants against O₃, neither by terms of foliar visible injury nor by terms of aboveground biomass. In addition, when applied at 10 and 50 ml dm⁻³ caused phytotoxicity to all the plants, which it was expressed as necrotic spots on the leaves’ surface, misshaping of the leaves, or short plants’ height_. It is obvious that vapor does not protect Bel-W3 tobacco plants against O₃. The antiozonate role of di-1-p-menthene is species-specific and probably occurs only under short-term exposures.