To assess the effect of septoplasty on pulmonary function test (PFT). 50 cases were chosen between the age group 18-50. All cases had nasal obstruction due to nasal septum deviation. Demographic data, detailed clinical examination including anterior and posterior rhinoscopy was performed. PFT values (fvc, fev1, fev1/fvc, fef25%, fef50%, fef75%, fif25%, fif50%, fif75%) were taken pre operatively and 1month after the surgery by using Helios 401 spirometer. All the data were recorded and spss version 20.0 was used to analyse the data. Among 50 patient, most of the patients were males 78% (n = 39) and the rest were females (n = 11) 22%. The patient were in between 18 and 50 age group. The maximum patient belonged to age group 18-27years (n = 25) 50% of the total patients. 38% (n = 19) were in the age group of 27-37years. 12% (n = 6) of the patients were in age group of 37-50. Nasal obstruction was present in all patients (n = 50) followed by sneezing (56%), nasal discharge (42%), and headache (26%). Maximum number of patient had deviation of septum to the left (n = 28) 56% and the rest had to the right (n = 22) 44%. After the surgery there was improvement in PFT values in all types of patient with DNS, but statistical significance was seen in type II in fef25% and fif75% values (p < 0.05). In rest of the patients there was no statistical significant improvement seen. A favorable outcome was seen in PFT values after Septoplasty, thus signifying the effect of deviated nasal septum on lower airway.