Although video-assisted thoracic surgery can be used for well-encapsulated thymomas, its role in invasive thymomas remains controversial. Between 1998 and 2009, 77 patients aged 22-76 years underwent thymomectomy by video-assisted thoracic surgery. Tumors <5 cm without major invasion on preoperative computed tomography were selected. There were 13 invasive thymomas (Masaoka stage III and IV). A modified dissection technique was employed to prevent breaching the tumor capsule and risking tumor seedling. Limited resection of the phrenic nerve, pericardium, perithymic fat, and a wedge of lung was performed en bloc with the tumor. The mean duration of surgery was 138 min. Hospital stay was 3.6 days. Eleven patients had associated myasthenia gravis. There was 1 case of wound infection and no operative mortality. The mean size of the thymomas was 34 mm (range, 23-55 mm). All patients had adjuvant radiotherapy. During follow-up of 4.9 years (range, 1-10 years), there was one local recurrence. With the modified video-assisted thoracic surgery technique, selected invasive thymomas detected during surgery can be removed safely without resorting to sternotomy.