Our endoscopic endonasal surgery, under the guidance of rigid endoscopes, aims at the primary focuses in the anterior ethmoid, clearing stenotic clefts and infected ethmoidal cells of diseased mucosa. The maxillary ostium is enlarged into the anterior nasal fontanelle to provide drainage and ventilation. There is no need for any fenestration into the inferior nasal meatus. Once the ethmoidal focus is cleared, the dependent larger sinuses usually heal without having been touched--even if their mucosal pathologies seemed almost irreversible. The endoscopic procedure, which except in children is carried out under local and surface anesthesia, is described in detail. Excellent results with this method, developed by Messerklinger, indicate that there is seldom need for a Caldwell-Luc operation as the state-of-the-art procedure in chronic recurring sinusitis.