Swyer-James-Macleod syndrome is a rare pulmonary disorder. It is characterized as a constrictive bronchiolitis resulting from loss of pulmonary vascularity secondary to a previous upper respiratory infection. We present the case of a 5-year-old boy who presented to the emergency department (ED) for acute asthma exacerbation. Radiographic imaging confirmed the diagnosis of Swyer-James-Macleod syndrome. The patient was admitted to the pediatric floor and treated with symptomatic management and discharged home after complete resolution of symptoms. Swyer-James syndrome is a rare disease that should be considered in individuals with recurrent pulmonary infections and hyperactive airway disease. Radiographic or computed tomography imaging is required in such patients for diagnosis. Swyer-James-Macleod syndrome is an extremely rare radiographic finding characterized by unilateral pulmonary hyperlucency. This diagnostic finding is a long-term sequela of bronchiolitis obliterans. Presentation of this syndrome is characterized by dyspnea, hemoptysis, reactive upper airway disease, and recurrent pulmonary infections. The etiology of this syndrome is diverse, as are its long-term effects. This rare disease causes a unique diagnostic challenge in the ED where the presenting sign is often an acute asthma exacerbation as witnessed in our patient. In the setting of both pediatric and adult patients, Swyer-James syndrome should be considered in patients with acute asthma exacerbation and a positive history of upper respiratory infections. A 5-year-old known asthmatic boy presented to the emergency department (ED) with chief complaints of wheezing and chest tightness of 1-day duration. Before presentation, the patient reported intermittent asthma for 2 weeks requiring daily use of albuterol. His symptoms worsened the day before presentation, when he began to cough and experience posttussive vomiting, chest tightness, and a tactile fever. The patient never became cyanotic or ashen. His symptoms did not improve after multiple albuterol treatments at home, after which he was brought to the ED. Medical history was positive for eczema and asthma. The patient reported allergies to egg, wheat, seafood, and animal dander. Family history was positive for asthma in both parents. There was no history of travel or sick contacts. Immunizations were up to date. At the ED, his temperature was 98.2°F; pulse, 148 beats per minute; respiratory rate, 18 breaths per minute; blood pressure, 112/79, with SaO 2 of 93% on room air. Physical examination revealed signs of moderate respiratory distress. Nasal flaring with supraclavicular, subcostal, and intercostal retractions were noted. Auscultation of the lungs revealed poor air entry with bilateral expiratory wheezing. The rest of the examination was unremarkable.