Nasal airway resistance (NAR), airway resistance through nose (TAR) and respiratory resistance through mouth (Rr. TM) were measured in 488 cases at three occasions; before, 1-2 weeks after and six months after intranasal operation, by a rhinograph (TUC-5600 M-type, Chest Co) using the oscillation method. The severity of chronic sinusitis as judged by X-ray findings corresponded well with the increased values in both NAR and TAR. Patients with septal deviation or hypertrophic lower turbinate showed elevated resistance. The nasal resistance was greater in K-shaped deviation than in C-shaped deviation. Postoperative NAR and TAR were found to have decreased to one half or one third of the preoperative level, but they increased again at six months after the operation. A tendency was noted that nasal operation decreases Rr. TM.