SUMMARYTo determine the value of ultrasound in identifying significant perforator disease we assessed 121 perforators in 90 legs of 61 consecutive patients referred for assessment of varicose veins over a 6 month period. Perforators greater than 4 mm in diameter demonstrated reflux in approximately 60% of cases, perforators 3‐4 mm in diameter demonstrated reflux in approximately 45% and perforators less than 3 mm in diameter demonstrated reflux in approximately 25% of cases.From correlation with previous published data we recommend that all perforators greater than 4 mm in diameter be considered incompetent regardless of whether reflux is demonstrate