The authors report the efficacy and adverse effects of intranasal ethmoidectomy in 70 patients with asthma and persistent severe symptoms from nasosinal polyposis despite repeated prior treatment. The efficacy was defined according to the evolution of symptoms and endoscopic findings. Adverse effects were evaluated according to subjective clinical and therapeutic data in all 70 patients. In addition, 25 patients had complete pre and post-operative pulmonary function tests. The results confirm that intranasal micro-surgery does not increase the severity of asthma. On the other hand, no significant improvement in bronchial function was noted after ethmoidectomy. Finally, the authors emphasize the poorer results obtained in Widal's disease and the importance, after the failure of medical treatment, of using of sufficiently extensive surgical procedure in order to decrease the incidence of recurrences.