OBJECTIVES: The Lund-Mackay score is widely used in assessment of chronic rhinosinusitis. We aimed to describe its relationship to other measures of pre- and post-treatment health status. STUDY DESIGN: Multicenter prospective study of 1840 patients undergoing surgery for chronic rhinosinusitis in the UK. RESULTS: There was no absolute threshold for surgery, but patients with higher Lund-Mackay scores underwent more extensive surgery. There was no correlation between Lund-Mackay and SNOT-22 scores. The Lund-Mackay increased with increasing grade of polyposis. The Lund-Mackay score was associated with symptom reduction (coefficient = 0.24, P = 0.02) complication rates (odds ratio, 1.08, 95%CI 1.06 to 1.1), and revision rates (odds ratio, 1.03, 95% CI 1.001 to 1.06). CONCLUSIONS: The Lund-Mackay score measures a different aspect of disease to "subjective" symptom scores. However, it correlates well with other markers of disease severity, the nature of surgery offered, and its outcome. SIGNIFICANCE: This demonstrates the strengths and limitations of a commonly used staging system.