Tolerance to aspirin was induced in thirteen asthmatics with aspirin-intolerance. Starting with the lowest aspirin doses eliciting bronchospasm, the dose of aspirin was progressively increased up to a 1000 mg tolerance level. Tolerance was rapidly achieved when initial threshold doses were greater than 150 mg. Daily aspirin administration led to prolonged tolerance. Desensitization to aspirin may be useful in aspirin-sensitive asthmatic patients who require antiinflammatory or antithrombotic treatment.