The distribution of venous reflux in patients with skin changes associated with chronic venous insufficiency presenting to a specialist clinic was assessed. A total of 300 limbs in 153 patients were examined by Doppler ultrasonography with colour-flow imaging for the presence of venous reflux in superficial veins, deep veins and medial perforating veins, both above and below the knee. Ninety-eight limbs had skin changes, which included hyperpigmentation, lipodermatosclerosis, atrophie blanche and ulceration. Of this group, 2 per cent had no evidence of venous reflux on duplex scanning, 39 per cent had deep vein incompetence, 57 per cent had superficial vein incompetence and 2 per cent had isolated medial perforating vein reflux. Of 25 limbs with ulceration, 13 had superficial and 12 deep vein reflux. A total of 202 legs, which included 20 normal control limbs, had no skin changes; 22.3 per cent of these had no venous reflux, 8.4 per cent had deep vein incompetence, 65.3 per cent had superficial incompetence and 4.0 per cent had isolated medial calf perforating vein incompetence.