All clinical trials in rhinosinusitis comparing levofloxacin to other agents, demonstrate levofloxacin to have consistent activity equal to or better than comparators (9-11). No clinical studies in rhinosinusitis show any agent to be better than levofloxacin. The problem with such trials is that a large number of patients are required to demonstrate superiority (12). If clinical success is the endpoint, almost 27,000 patients are required to demonstrate superiority of an agent with 90% killing activity compared to one with 80% efficacy. However, if double tap bacteriological studies are performed, the number of patients required is less, but still a substantial number.