We report the treatment and outcomes of 12 patients who underwent subfascial endoscopic perforator surgery for severe chronic venous insufficiency and venous ulceration. All patients had received prior superficial venous ablative surgery and presented with incompetent perforating veins in the calf and persistent venous ulceration (lasting >10 years). Outcome measures included ulcer healing time, recurrence, clinical symptom, and disability scores. There was one wound complication after subfascial endoscopic perforator surgery. The cumulative ulcer healing rate was 25% at 3 months, 42% at 6 months, and 92% at 1 year. One patient developed ulcer recurrence at 12 months after surgery. The mean clinical score and disability score decreased from 13.00 (standard deviation, 2.26) to 4.83 (1.47) and 1.75 (0.45) to 0.50 (0.52), respectively (P<0.001) after a median follow-up of 15.0 months (interquartile range, 12.0-21.5 months). Subfascial endoscopic perforator surgery was safe and effective in the treatment of patients with severe chronic venous insufficiency and venous ulceration caused by incompetent perforating veins in the calf.