Unilateral diaphragmatic paralysis is a condition that can lead to respiratory dysfunction and, in extreme cases, death. Presents similar etiology to paralysis of bilateral involvement, and in many cases, are idiopathic. Therefore, have considerable diagnostic not index. Has wide range of clinical manifestations, ranging from asymptomatic episodes’ frames with respiratory failure. This article makes a bibliographical review about the main features of unilateral diaphragmatic paralysis (UDP), highlighting the most relevant data about definition, etiology, pathophysiology, clinical presentation, diagnosis and more effective treatment of this illness to systematize the knowledge about this disease.