The conflicting information related to oxidative stress status in patients with chronic idiopathic urticaria has been reported in several studies. However, the association between acute urticaria (AU) and oxidative stress has not been investigated exhaustively. To evaluate the role of the oxidative stress in the patients with AU by determining the oxidant/antioxidant activity in AU and to establish its clinical significance. About 50 patients with AU, (10 males, 40 females) and 30 unrelated healthy controls (4 males, 26 females) were enrolled into the study. The activity of the antioxidant enzymes copper-zinc superoxide dismutase (Cu-Zn-SOD), glutathione peroxidase (GSH-Px) and catalase, and the levels of malondialdehyde (MDA), serum NO and protein carbonyls levels in the plasma were measured spectrophotometrically at samples. A statistically significant increase was observed in serum Cu-ZnSOD activities of the patients when compared with that of the controls (p < 0.001), while a statistically significant decrease was observed in GSH-Px activities of the patients according to the controls (p = 0.002). Serum MDA and NO levels were significantly higher in patients with AU when compared with control group (p < 0.001 for both of them). The levels of protein carbonyls were significantly lower in patients with AU when compared with control group (p < 0.001). It seems there is an oxidative burden in the patients with AU. Cutaneous oxidative stress may play a role in pathogenesis of the disease.