The purpose of this study was to evaluate some oxidative stress indicators of horses exposed to transport stress. The study was carried out on 10 healthy mixed breed adult horses, transported by road on 538 km. Physical (rectal temperature, respiratory and heart rates), haematological, biochemical and oxidative stress (Malonedialdehyde (MDA) and superoxide dismutase (SOD)) parameters were determined before and after transportation. The transportation has induced significant (P < 0.05) increases in respiratory and heart rates, in haematocrit and in glycaemia, the other clinical, haematological and biochemical parameters remaining unchanged. The occurrence of an oxidative stress induced by a 12 hour transport period was evidenced by a marked and significant increase of the plasma MDA concentrations coupled to a significant reduction in the plasma SOD activity compared to baseline values. In conclusion, the long-distance transport has negatively affected the oxidant/antioxidant status in horses.