Diaphragmatic plication is technically simple using a conventional operative technique, but it requires a large skin incision and rib injury. We present an alternative technique for thoracoscopic plication of the diaphragm and evaluate the advantages of the procedure. Six patients (five with diaphragmatic eventration and one with diaphragmatic hernia with a sac) ranging in age from 8 to 20 months were treated by this method. Three of the six cases were right-sided, and three were left-sided. The operation was performed under artificial pneumothorax using carbon dioxide gas at 4 mmHg. Three trocars for laparoscopy were inserted at the 4th and 5th intercostal spaces. An adequate operative view was obtained by pressing the diaphragm throughout the operation. The eventrated diaphragm was plicated with several rows of nonabsorbable sutures in the anterolateral-to-posterolateral direction to prevent injury to the main phrenic nerve. A tight diaphragm was confirmed by decompressing the artificial pneumothorax. The technique was successfully performed in all cases, and the patients' postoperative courses were uneventful. During the operation, the hemodynamic effects of carbon dioxide gas at 4 mmHg were minimal. Over a mean follow-up period of 3.1 years (range, 1-6 years), no recurrence of diaphragmatic eventration was seen. Judging from the satisfactory postoperative course, this procedure is suitable for children with all forms of diaphragmatic eventration.