First described by Jean Louis Petit in 1774, eventration is the abnormal elevation of all or a portion of a diaphragmatic leaf, which then does not participate in respiratory activity. Total eventration of a hemidiaphragm is a rare anomaly in adults. This condition usually results from primary or acquired phrenic nerve palsy but often presents as a pure degenerative muscular disease without evident signs of denervation. Generally, the disease is a true congenital defect acquired during the fetal period associated with hypoplasia of the lung on the involved side, with appearance of severe cardiorespiratory symptoms at birth. Acquired total diaphragmatic eventration is an uncommon condition. Eventration that occurs in adults is caused by acquired complete or incomplete palsy of a diaphragmatic leaf, often after head and neck operations or cardiovascular procedures, but it has also been described in trauma, motor neuron diseases, infection, and neoplastic infiltration.