Benign neoplasms and cysts are the most common tumors of the mediastinum. However, they are still an infrequent clinical entity. Their diagnosis has been aided by the recent advances in CT scanning, MRI, ultrasonography, radionucleotide scanning, and fine-needle aspiration. The treatment of these benign tumors in children and the majority of adults is excision. In asymptomatic adults, observation or fine-needle aspiration and observation may be considered for pericardial cysts and selected neurogenic tumors and bronchogenic cysts.