The aim is to investigate the contribution of the PNIF test in daily clinical practices in the objective evaluation of the early postoperative functional results of septoplasty and the effect of the severity, direction, and type of nasal septum deviation on mean PNIF values. Nasal septum deviation (NSDs) of the cases were grouped according to the Mladina classification and the severity of NSDs. An objective evaluation of the nasal airway was conducted via a peak flowmeter device in the preoperative and postoperative first month. When examining the mean PNIF values according to genders, it was observed that the values determined in male cases in the preoperative and postoperative period were higher. In the intragroup evaluation performed according the Mladina classification, a statistically significant increase was observed in the preoperative and postoperative PNIF values of the cases in Types 1-4. In the intragroup evaluation performed according to the severity of NSD, there was a significant increase in the preoperative and postoperative PNIF values of the mild and moderate cases. When comparing the preoperative and postoperative PNIF values of the groups in terms of the severity of NSD, it was observed that there was a significant difference. The PNIF can be used in routine clinical practices to evaluate the septoplasty results objectively. In the evaluation of functional results, the change in the mean PNIF values may also vary according to the direction and severity of septum deviation and the Mladina classification other than age, gender and ethnic origin.