Seven adult patients with dyspnea resulting from nonmalignant unilateral diaphragmatic paralysis underwent plication of the affected hemidiaphragm. Preoperatively, the patients complained of exertional dyspnea and orthopnea and had a reduced arterial oxygen tension, total lung capacity, vital capacity, expiratory reserve volume, and functional residual capacity. Plication was performed by imbricating the diaphragm in layers through a thoracotomy. After plication there was a significant increase in arterial oxygen tension and all lung volumes except residual volume. The patients' symptoms were improved with plication and a significant decrease was recorded in breathlessness on a visual analogue scale. There were no postoperative complications and mean hospital stay was 12 days.