BACKGROUND Aspirin-sensitive patients with asthma experience continuous inflammation of their nasal and sinus tissues, complicated by recurrent sinusitis, which frequently leads to asthma attacks. Systemic corticosteroid therapy and sinus or polyp surgery are currently required to control underlying rhinosinusitis, and bursts of corticosteroids are used for asthma control. OBJECTIVE After aspirin desensitization therapy, objective measures of respiratory disease activity, linked to the need for systemic corticosteroids and sinus surgery, were studied to determine whether any changes occurred. METHODS Sixty-five aspirin-sensitive patients with asthma underwent aspirin challenge, followed by aspirin desensitization and daily treatment with aspirin over 1 to 6 years (mean, 3.1 years). Clinical outcome measurements before aspirin desensitization treatment and during follow-up were analyzed for the larger group of 65 patients and subgroups (29 patients receiving therapy for 1 to 3 years and 36 patients receiving therapy for 3 to 6 years). RESULTS In the larger group of 65 patients, there were significant reductions in numbers of sinus infections per year (median, 6 to 2), hospitalizations for treatment of asthma per year (median, 0.2 to 0), improvement in olfaction (median, 0 to 2), and reduction in use of systematic corticosteroids (mean, 10.2 to 2.5 mg) with p values less than 0.0001. Numbers of sinus and polyp operations per year were significantly reduced (median, 0.2 to 0; p = 0.004), and doses of nasal corticosteroids (in micrograms) were significantly reduced (mean dose, 139 to 106 micrograms, p = 0.01). Emergency department visits and use of inhaled corticosteroids were unchanged. CONCLUSIONS The results support a role for aspirin desensitization treatment of aspirin-sensitive patients with rhinosinusitis-asthma.