Nocardiosis is a rare infectious disease caused by bacteria of the genus nocardia, which causes considerable morbidity and mortality. We report two unusual cases of nocardiosis in young, immunocompetent patients; the first case involved a nocardia farcinica pulmonary and chest-wall infection, while the second was an anterior mediastinal nocardia asiaticum infection mimicking a mediastinal tumor. These cases reflect the need for a broad differential diagnosis during exploration of thoracic findings, white the potentially ambiguous presentation of nocardiosis must be considered.