Endobronchial carcinoid tumor is the most common malignant pulmonary tumor of the childhood tumors, accounting for 50 to 80% of childhood tumors. Endobronchial carcinoid tumor is generally accompanied by symptoms such as cough, hemoptysis, wheezing, weight loss, dyspnea, and chest pain, as well as by radiological symptoms including atelectasis, sclerosing lesion, infiltration, and lump patterns. This case report is about a patient whose asthma had been treated for several years but was not properly regulated, and who showed a unilateral overinflation in the chest x-ray that was diagnosed as an endobronchial carcinoid tumor after additional tests. CASEA 14-year old, male, child patient who had been undergoing treatment for asthma in another hospital for three years due to repeated coughing, wheezing, and dyspnea visited our institution. The patient was hospitalized due to the exacerbation of his coughing, wheezing, and dyspnea, and underwent treatment using a bronchodilator, steroids, and a leukotriene receptor antagonist. However, since the Results: This case describes a 14-year-old boy, presenting with asthma-like symptoms throughout 3 years. He was treated as asthma but wax and wane. Chest x-ray showed an hyperlucent left lung, so we rechecked high resolution computed tomography (HRCT) for unilateral hyperinflation diseases diagnosis. It was found 1×1㎝ nodule in left main bronchus. We did bronchoscopy and discovered a round mass in the left bronchus, 2∼3㎝ away from carina. In the biopsy, it was bronchial carcinoid tumor, so we resected tumor. Discussion: Because symptoms of bronchial carcinoid tumors are various, it can often be misdiagnosed firstly. It is confused with asthma, pneumonia and foreign body. An additional examination were necessary when respiratory symptoms persist.