Ramos VM, et al. - In this prospective study, researchers intended to determine the effect of adenotonsillectomy on nasal airflow and pulmonary blood pressure in mouth breathing children. The study sample consisted of 30 children between 2 and 12 years of age, with an indication for adenotonsillectomy due to adenotonsillar hyperplasia, assessed before and 6 months after surgery and 29 nasal breathing children in the same age group. Data reported that the mean pulmonary artery systolic pressure (PASP) among mouth breathing children was 25.99 mmHg, with a Standard Deviation of (±) 3.27, in the preoperative period and 21.79 mmHg (±2.48) in the postoperative period. It was noted that the mean pre-operative total inspiratory nasal airflow (TINAF) was 266.76 cm³/s (±112.21) and 498.93 cm³/s (±137.80) after surgery. According to results, the values of PASP and TINAF improved postoperatively and correlated inversely. This research indicates that there has been a decline in PASP by enhancing TINAF.