Background: Diaphragmatic plication through a thoracoscopic approach has been an effective modality to treat diaphragmatic enventration. However, the conventional technique for thoracoscopic plication has some disadvantages. We have developed an improved and simplified technique with utilizing the head up position, CO₂ insufflation and figure-of-eight sutures. Material and Method: Between October 2005 and September 2009, 9 patients with diaphragmatic paralysis underwent repair using our modified technique. The mean patient age was 38.5±53.0 years (range: 2~76 years). Result: The mean operation time was 46.7±15.9 min (range: 30~85 min). None of the patients died due to this procedure, but there was one case of prolonged air leakage, and a case of re-expansion pulmonary edema, which required 3 days of ventilator support after the procedure. The mean hospital stay was 6.22±2.04 days (range: 4~11 days). The mean follow-up duration was 27.2±11.6 months (range: 2~43 months). All the patients had their symptoms relieved and there was no recurrence of eventration except for one patient who developed more than 2 ㎝ elevation of the diaphragm compared to the immediate post-operation status. Conclusion: With our technique, thoracoscopic diaphragmatic plication was feasible via using only three 5 ㎜ ports and without a working window and the midterm results were favorable. Therefore, we advocate thoracoscopic diaphragmatic plication as a preferred technique to the conventional open plication technique.