Using objective and subjective criteria, we performed a study to assess the long-term impact of functional endoscopic sinus surgery (FESS) in patients with chronic rhinosinusitis and asthma at an average follow-up of 6.5 years. One hundred twenty patients who underwent FESS for chronic rhinosinusitis were followed up for an average of 6.5 years (range 6.0 to 10.6 years). Seventy-two (60%) patients responded to a follow-up questionnaire, and 30 (42%) of them reported a history of asthma. Subjective levels of improvement and assessments of medication need were evaluated and statistically assessed with parametric and nonparametric methods. Of these 30 patients, 27 (90%) reported that their asthma was better than it had been before FESS, 6.5 years ago. Average reported improvement increased from 49% at 1.1 years after surgery to 65% at 6.5 years after surgery. Asthma attacks declined in 20 of 27 (74.1%). Medication use for asthma showed similar improvement, with approximately half reporting less inhaler usage and nearly two thirds reporting less oral steroid use. This study demonstrates that a combination of FESS, careful postoperative care, and appropriate medical therapy for chronic rhinosinusitis has a favorable long-term effect on asthma in patients with symptomatic chronic sinusitis. In this study asthma severity, frequency of attacks, and medication need were all improved.