Surgical treatment of eventration or paralysis of the diaphragm is symptomatic and non curative, and depends on whether the dysfunction is of peripheral or central origin. Elevation of a hemidiaphragm of peripheral origin, the most frequent situation, needs surgical treatment only in case of major functional effects (effort or positional dyspnoea, cardiac or digestive symptoms, or pain) that persists despite optimal conservative management. Selection of candidates for surgery depends on a thorough morphological and functional investigation of the neuromuscular and respiratory components. Surgical plication of the diaphragm through a lateral thoracotomy or by video-thoracoscopy is a recognized, safe and effective procedure. Its low morbidity and mortality, which are mainly associated with co-morbid factors, and its long-lasting functional benefit of around 100%, show that it is an effective procedure. In the case of bilateral dysfunction, occasional cases of bilateral plication have been reported. Some cases of diaphragmatic paralysis of central causation result in a life of ventilator dependence, even though the peripheral neuromuscular and respiratory systems are intact. In selected cases, following a complete functional investigation, phrenic nerve pacing may be attempted to achieve ventilator weaning. To date, there are two validated indications for this technique: Tetraplegia above C3 and alveolar hypoventilation of central cause. After thoracic implantation, a progressive reconditioning of the diaphragmatic muscle allows weaning from the ventilator in a few weeks in more than 90% of patients. Their quality of life is greatly improved thanks to independence from the ventilator, more physiological respiration, restoration of smell and better speech. Whether the diaphragmatic dysfunction is peripheral or central in origin, the success of surgical treatment depends on rigorous preoperative selection of patients.