Recurrent venous reflux in the popliteal fossa of patients with recurrent varicose veins following short saphenous vein surgery was assessed in 70 limbs using a duplex scanner. Incompetence of the short saphenous vein was found to be the main source (61%) of venous reflux in the popliteal fossa (43/70). The recurrence or persistence of the short saphenous vein was subdivided into four types: an intact saphenopopliteal junction, as well as an intact short saphenous vein in 20 limbs (type I): varicosities in the popliteal fossa communicating with a short saphenous vein stump in 11 limbs (type II); a residual short saphenous vein communicating with the popliteal vein via a tortuous recurrent vein in eight limbs (type III); and a segment of residual short saphenous vein with no communication with the popliteal vein in four limbs (type IV). Incompetence of a gastrocnemius vein was involved in 24 cases (34%), an incompetent popliteal area vein in one (1.4%), popliteal vein incompetence in 15 (21%), and popliteal fossa varicosities communicating with the long saphenous system in two (3%). Of 12 limbs tested pre- and postoperatively, a high termination of the short saphenous vein was demonstrated in four of seven residual incompetent short saphenous veins. Duplex scanning is recommended to assess recurrent venous reflux in the popliteal fossa. It can be used to determine the level of an incompetent saphenopopliteal junction and the level of the termination of any other incompetent vein in the management of varicose veins recurring after a short saphenous vein operation.