Exercise-induced laryngeal obstruction (EILO) is one of many different causes for adolescents to experience dyspnoea during exercise. Objective exercise-testing with continuous video laryngoscopy is crucial for a correct diagnosis since it is difficult to differentiate EILO from other exercise related conditions in the airways only on the symptomatology. The main symptom in EILO is inspiratory stridor arising from an obstruction at the laryngeal level during ongoing exercise which quickly resolves after the exercise has stopped. EILO is often misdiagnosed as exercise-induced bronchoconstriction (EIB), which is obstruction in the peripheral airways that typically arises after cessation of exercise. From a previous survey investigating self-reported exercise-induced dyspnoea in all 12-13-year-old adolescents in Uppsala (n=3,838, response rate 60.2%) a subset of 150 randomly selected adolescents (103 with dyspnoea and 47 controls) performed standardized treadmill exercise-tests for EIB and EILO. During the exercise-test for EIB the subjects breathed dry air according to the current recommended guidelines. EIB was defined as a decrease in FEV1 ≥10% from baseline. EILO was diagnosed during a continuous laryngoscopy exercise (CLE) test by use of the CLE-score method and was defined as an obstruction of grade 2 at either glottic or/and supraglottic laryngeal level. The estimated prevalence of EIB in the general population was 19.2% and the estimated prevalence of EILO was 5.7%. No gender differences were detected. A diagnostic software program for EILO, EILOMEA, was compared with the CLE-score and the methods were found to be compatible. EILOMEA was used to map and compare laryngeal response patterns in adolescents with exercise-induced dyspnoea (EIB and/or EILO), in adolescents with dyspnoea but without a diagnosis of EIB or EILO, and in healthy controls, all of whom had performed the CLE-test. No differences were seen between the healthy controls and the adolescents with dyspnoea without a diagnosis. Only adolescents diagnosed with EILO showed a significant different laryngeal response pattern which strongly suggests that the diagnostic procedure is reliable. In a follow-up study of patients referred for investigation of exercise-induced dyspnoea, we investigated the outcome of surgical vs. conservative treatment of EILO-positive subjects and subjects tested negative for the diagnosis, regarding the level of exercise-induced dyspnoea and physical activity. Surgically treated patients had less breathing problems and were more physically active than both conservatively treated patients and patients who were tested negative.