The effect of capsaicin treatment (intraperitoneally) on the pulmonary anti‐oxidant enzyme system has been studied using rats as experimental animals. Short‐term treatment with capsaicin has been found to cause a significant increase in superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities. On the other hand, long‐term treatment with capsaicin produced a significant decrease in CAT and POD activities. This result has been interpreted in terms of the already reported ‘activation’ and ‘densensitization’ action of capsaicin on short‐ and long‐term treatment respectively. Copyright © 1989 John Wiley & Sons, Ltd.