For some patients, traditional or functional endoscopic sinus surgery (FESS) fails to relieve persistent or recurrent sinus disease. This subset of patients may require revision surgery. The objective of this study was to define and evaluate which features of sinus disease and prior treatment were characteristic of patients requiring revision FESS. Within a series of 295 consecutive FESS procedures, 43 patients who had prior sinus surgery and required revision FESS were studied and followed for a mean 14.1-month period. The characteristics of 13 patients with persistent disease following revision FESS and the potential technical risks and complications encountered were also evaluated. This study concludes that revision FESS is a safe technique that was effective in 69.8% of the patients, and that certain factors may predict a poor surgical outcome.