A consecutive series of 118 patients (148 legs) presenting with recurrent varicose veins underwent preoperative clinical and hand-held Doppler ultrasonographic examination by a single observer. The presence of saphenofemoral, mid-thigh perforator and saphenopopliteal reflux was noted. Ultrasonography markedly improved the accuracy of clinical assessment at all three potential sites of reflux compared with operative findings. Of 71 patients undergoing repeat groin dissection, only 20 (28 per cent) had a tied saphenofemoral junction, 31 (44 per cent) had intact major tributaries and 52 (73 per cent) had an intact long saphenous vein (LSV) in the thigh. There was a positive association between mid-thigh perforator reflux giving rise to recurrent varices and the presence of an intact LSV in the thigh. Of 45 legs with saphenopopliteal reflux, only four had previously undergone saphenopopliteal ligation, suggesting that most short saphenous varicosities had either appeared after or had not been recognized at the time of primary surgery. This study indicates that even an experienced vascular surgeon can have difficulty in assessing the presence or absence of recurrent deep to superficial reflux by means of clinical examination alone and that Doppler ultrasonographic examination is mandatory. Recurrence continues to be associated with persistent or recurrent incompetence at the site of previous inadequate surgery.