One hundred nine patients with chronic rhinosinusitis underwent functional endoscopic sinus surgery. Seventy seven patients had polyposis. The population was studied prospectively for 5 years postoperatively. Seventy two patients attended the 5 year follow-up visit. At 1, 2, 3, 4 and 5 years of follow-up all outcome measures except olfactory detection thresholds (visual analogue scores, endoscopic findings, nasal mucociliary clearance times, total nasal volumes) were significantly improved compared to preoperative baseline values. Olfactory detection thresholds were significantly improved at 1 and 2 years postoperation. Patient symptom scores were improved in a greater percentage of patients than more objective outcome measures. Thirty eight patients required a total of 88 postoperative rescue medication courses with prednisolone and antibiotic. Twelve patients failed the study as they required at least 1 rescue medication course a month for 2 consecutive months. We demonstrated an 89% 5 year "survival" rate with regards to the risk of failure. The patients were also entered into a randomised, stratified, prospective, double-blind, placebo controlled study of fluticasone propionate aqueous nasal spray 200 mcg twice daily, commencing 6 weeks after FESS, with a 5 year follow-up. The change in overall visual analogue score was significantly better in the FPANS group at 5 years. The changes in endoscopic oedema and polyp scores and in total nasal volumes were significantly better in the FPANS group at 4 years but not 5 years. Last value carried forward analysis demonstrated that changes in endoscopic polyp score and in total nasal volume was significantly better in the FPANS group at 5 years. Significantly more prednisolone rescue medication courses were prescribed in the placebo group. Of the 12 patients who failed the study, 10 were in the placebo group. This difference nearly achieved significance.