Two cases of cystic hygroma in adults are presented. In the first case, the lesion was in the right paratracheal region, and in the second case in the left paracardiac region. Excision of the cystic mass was performed in both cases. The diagnosis of cystic hygroma was confirmed by histological examination. The mediastinal type of cystic hygroma is rare and is usually not discovered until adulthood. Thorax computed tomography findings are not specific. There is no effective treatment other than surgical excision.