Reactive oxygen species can participate in the airways reactivity changes after oxidants. The authors have observed an increase in airways reactivity after an exposure to toluene in guinea-pigs and cats in previous experiments. There literature data provide information on the prevention or the delay of free radical damage by antioxidants.The aim of our study was to evaluate the effect of nonenzymatic antioxidants--vitamin C and vitamin E on the airways reactivity changes after the exposure to toluene vapours.After a one-month-lasting pretreatment with 500 mg/kg/day vitamin C and 50 mg/kg/day vitamin E the guinea-pigs were exposed to toluene for 3 days 2 hours. Then the reactivity of trachea and lung strip smooth muscle to histamine was evaluated.The pretreatment with vitamin C did not evoke statistical significant changes of trachea and lung strip smooth muscles reactivity when compared with the control group. The pretreatment with vitamin E produced a statistically non-significant decrease in trachea smooth muscle reactivity, but an increase in contraction amplitude of lung strip smooth muscle. Trachea was without expressive histological changes. The lung showed granulomatous inflammation with lymphocytes and eosinophils.Antioxidants in used doses did not prevent the reactivity changes evoked by toluene exposure. (Fig. 2, Tab. 4, Ref. 14.)