Oxidative processes, mediated by oxygen free radicals are recognized to contribute significantly to the inflammatory pathology of bronchial asthma. An imbalance between oxidants and antioxidants has also been proposed in this disease. This study examines the serum total antioxidant status (TAS) in asthmatic patients with severe exacerbation of their disease and the probable correlation with clinical or laboratory findings. The TAS was measured in 20 patients (10 men and 10 women, with a mean age of 41.95 +/- 20.75 years), using a colorimetric method. On the days of admission and discharge, the forced expiratory volume in 1 sec (FEV1), the partial arterial oxygen pressure (PaO2), and severity criteria were recorded and correlated with TAS at the same time. The TAS was also measured in 10 healthy subjects (8 men and 2 women, mean age of 39 +/- 9 years). A statistically significant decrease of TAS was observed on admission day compared to that on discharge day (0.98 +/- 0.08 vs. 1.12 +/- 0.17 mmol/L, p < 0.001, respectively, paired t-test) suggesting the presence of oxidative stress during an asthma attack. The TAS on admission was also statistically significantly decreased compared to that of normal subjects (0.98 +/- 0.08 vs. 1.19 +/- 0.09 mmo/L, p < 0.001, respectively, paired t-test). A statistically significant correlation was observed between FEV1 change and TAS change, from admission to discharge day (r = 0.58, p = 0.007, Pearson correlation). Finally, a statistically significant correlation was found between FEV1 change and TAS on discharge day (r = 0.65, p = 0.002). Decreased TAS was found during an asthma attack, probably as a consequence of increased oxidative stress. The TAS change was correlated with severity criteria, such as FEV1. Therefore, it seems that measurement of TAS could be a simple and useful tool in the evaluation of an asthma attack. The supplementary administration of antioxidants in future needs further clarification.