Endoscopic sinus surgery (ESS) has undergone exponential growth worldwide in the last decade. It is now accepted as a safe and effective means of treating sinonasal disease. The purpose of this study was to determine whether post-operative debridement is necessary after ESS. Seventeen patients undergoing bilateral primary ESS were randomized to receive debridement of either the left or right ethmoid cavity. All patients included in the study had symmetrical disease. Saline douches and all other concomitant treatments were delivered bilaterally. Outcome measures were based on regular symptom scores and surgeons' semi-quantitative assessment of the debrided and non-debrided cavities, over a three-month period. Analysis of adhesion rates, healing and symptom scores showed no statistically significant difference between the two groups. In conclusion, this study did not demonstrate significant benefit from post-operative ESS cavity debridement, at least with regard to cavity healing. This should be considered a pilot study and therefore limited conclusions can be drawn. Further work is needed to determine the optimum post-operative care for ESS.