We studied effects of 7-h exposure of 70 ppb ozone during early developmental stage on three monocotyledonous crop species: oat (Avena sativa), wheat (Triticum aestivum) and barley (Hordeum vulgare). After fumigation, levels of low molecular weight antioxidants, Trolox equivalent antioxidant capacity (TEAC) and superoxide dismutase-like activity (SOD) were examined. It has been concluded that ozone exposure caused negative effects on these cereals, although each cereal seemed to be affected differently. In contradiction to the generally held idea that young seedlings are not susceptible to ozone, we found effects of the short ozone episode on antioxidant capacity. There was an induction of TEAC in barley and of SOD-like activity in oat, while a decrease of TEAC was found in wheat and oat. Although no clear mechanistic scheme can be set up demystifying the results, it was proven that young seedlings can be influenced by low level ozone pollution. This information might be important when considering general effects of air pollution on monocot crop species.