The authors report 2 typical asthmatic cases in whom the administration of acetylsalicylic acid (ASA) and nonsteroid anti-inflammatory drugs (NSAID) resulted in bronchodilatation. 500 mg of ASA were administered intravenously to 1 patient and the other was treated with ASA, indomethacin, noramidopyrine intravenously and acetaminophen orally during a bronchospastic attack. FEV1 and SRAW were measured before and after drug administration. The test was repeated with placebo (physiological saline). FEV1 increased rapidly after ASA and NSAID administration. Although the pathogenesis of asthma reversed by aspirin is not entirely clear, the authors suggest an alteration of sensitivity of the cyclo-oxygenase enzyme due to the inhibitory action of ASA and NSAID.