ALTHOUGH SINUSITIS triggers billions of dollars of health care expenditure each year, surprisingly little is known about its epidemiology, pathophysiology, and management. Sinusitis, a disease that affects all age groups, varies from an acute infection following a viral respiratory tract infection to an unremitting chronic problem, such as found in children with cystic fibrosis. Although bacteria have been cultured routinely from about two thirds of patients with acute sinusitis,1 the role of bacteria in chronic sinusitis has not been well defined.