Swyer-James-MacLeod syndrome is a rare pulmonary disorder that exhibits unilateral hyperlucency of a part of or the entire lung and because it is usually asimptomatic the diagnostic of this illness is discovered accidentally after a chest X-ray. Although the cause of this disorder is not completely understood, most authors believe that this is due to late sequela of infectious bronchiolitis that occurs during childhood. The symptoms presented by the individuals are often scarce at the moment of diagnostic, but a history of recurrent episodes of pulmonary infection accompanied by dyspnea, hemoptysis and/or chronic productive cough should raise the suspicion for such a diagnosis. Swyer-James-MacLeod syndrome can be interpreted as asthma or pulmonary embolism and this can result in inappropriate therapy. This case report describes a 38-year-old patient with chronic respiratory symptoms diagnosed on the findings of the chest X-ray and high resolution CT.