Asthma is one of the most common chronic medical conditions affecting children. The usual presenting symptoms of asthma include wheezing, shortness of breath, and dyspnea on exertion. Occasionally, children who present with one of these respiratory complaints have a less common disorder. Mediastinal fibrosis is a rare and incurable condition in which an excessive fibrotic reaction in the mediastinum causes progressive cardiopulmonary compromise. The presentation is variable: many patients present with respiratory symptoms such as cough, wheezing, dyspnea, and/or hemoptysis, while others are asymptomatic and present with a mediastinal mass discovered incidentally on a radiograph. With such a broad array of presenting complaints, and a clinical course characterized by slow progression of symptoms, the early stages of mediastinal fibrosis can mimic other diseases such as asthma, chronic bronchitis, or the superior vena cava syndrome. In this report we describe two patients with mediastinal fibrosis who were initially thought to have asthma.