It is becoming increasingly important for clinicians to be able to demonstrate the effectiveness of their interventions. We have developed a rhinosinusitis--specific outcome measure (SNAQ-11) that avoids the shortcomings of the existing tools. This paper compares its use with the widely used Sinonasal Outcome Test (SNOT-20). We carried out a prospective study that involved forty patients undergoing endoscopic sinus surgery. Their SNAQ-11 and SNOT-20 scores were compared pre and post operatively. We also recorded individual symptom scores pre and post operatively in order to study the impact of surgery. The study shows a larger change in the postoperative SNAQ score compared to that in SNOT-20 (21% c.f. 11%) Although the pre and post-op changes in SNOT-20 are significant at the p = 0.005 level, the changes in the SNAQ-11 are highly significant at the p = 0.0001 level. Furthermore we have statistically confirmed that the change seen with SNAQ-11 is larger in relation to the variation in change as compared with SNOT-20 (-1.08 c.f. -0.59). Our results show that SNAQ-11 is a valid and highly relevant rhinosinusitis outcome tool. The results also confirm that Endoscopic Sinus Surgery seems especially effective at addressing nasal obstruction, congestion and facial pain/pressure, fair at anterior nasal discharge, sneezing, hyposmia and sleep disturbance and poor for post nasal drip, cough and earache.