Over an 18-month period, of 444 patients referred for treatment for varicose veins, 95 (21%) had had previous surgery. By means of clinical hand-held Doppler and in selected venographic evaluation these were subdivided into three groups as follows. Type 1:29 of the 95 patients had recurrence through thigh perforators. Type 2:10 patients had developed incompetence through a second saphenous system, in nine of the 10 in the short saphenous having had previous long saphenous surgery. Type 3:46 patients had recurrent sapheno-femoral incompetence and 10 sapheno-popliteal incompetence. A persistent long saphenous trunk in the thigh was present in approximately two-thirds of cases of types 1 and 3. In over half of the type 3 patients saphenofemoral recurrence was by reconstitution of the junction by neovascularisation. These morphological studies demonstrate why there may be an increased risk of recurrence if the long saphenous trunk is not excised at the time of primary surgery.