In terms of functional treatment of sinonasal pathologies, endoscopic surgery represents a spectacular advance, offering excellent illumination, views of areas previously impossible to monitor, and the ability to view the main reference points in the surgical field. Over a five-year period (1988-1993), the authors have performed 278 paranasal sinus operations, using endoscopic techniques. The results obtained in 250 patients, with a minimum follow-up period of one year, have been analyzed. The criteria of assessment used include: self-assessment by the patient and the surgeon's assessment, made on basis of the endoscopic data. The best results were obtained in cases of antrochoanal polyps, polyposis not associated with asthma or acetylsalicylic acid (ASA) sensitivity, circumscribed chronic sinusitis, and aspergillomas. The worst results, with a high rate of recurrence, have been obtained with ASA sensitivity and chronic suppurative pan-sinusitis. It is essential to reach a consensus on the staging of polyposis so that treatment can be monitored adequately, even though, in itself, the pathology is difficult to classify as it can vary in a single patient for no apparent reason. On the other hand, there is a difference between the subjective and objective assessment of the condition, and this makes it even harder to explain the results obtained.