A patient with a bronchogenic cyst in the mediastinum is presented. This rare cyst was found by chance in a 14-month-old boy suffering from respiratory distress due to partial compression of a bronchus. Ultrasonographic and tomographic examinations revealed a cystic mass measuring 3 x 3 cm in diameter located within the apex of the right lobe of the lung. Bronchogenic cyst should be considered when these signs present in early childhood.