In 54 patients with unilateral leg ulceration of purely venous aetiology the only difference in venous reflux between affected and non-affected legs was with respect to the popliteal and crural veins. Deep and superficial venous reflux is common in legs without the skin changes typical of chronic venous insufficiency. The significance of venous reflux in an ulcerated leg cannot therefore be determined without reference to the contralateral, clinically normal, limb. Surgery should be directed at correcting reflux present in the ulcerated limb but not in the unaffected limb. In a minority of patients this entails superficial venous surgery alone, but in the majority such an approach would, ideally, entail correction of deep venous incompetence.