Frontal sinusitis follows upper respiratory infections, sinus trauma, and swimming. Complications, often life threatening, still occur although less frequently than in the pre-antibiotic era. The course of 40 patients admitted to St. Michael's Hospital with a diagnosis of frontal sinusitis between the years 1973-83 is reviewed. The regional complications as well as the surgical procedures required to manage these problems are discussed. The osteoplastic flap with obliteration of the sinus cavity by osteoneogenesis has become the procedure of choice in dealing with most cases of chronic frontal sinusitis.