OBJECTIVE: The purpose of this study was to correlate the clinical findings in the Edinburgh Vein Study with the results of duplex scanning of the deep and superficial venous systems. METHODS: An age-stratified random sample of 1566 people (699 men and 867 women) aged 16-64 were selected from computerized age-sex registers of participating practices (twelve general practices with catchment areas geographically and socioeconomically distributed throughout Edinburgh). Screening included clinical examination, photography and duplex ultrasonography of the superficial veins and the deep veins down to popliteal level. Telangiectasia and varicose veins were graded 1-3 according to severity. RESULTS: Since there was good agreement between the duplex findings of the right versus left legs, the current analyses are based on 1092 subjects (486 men and 606 women) with complete duplex scan data in their left legs. There was no significant trend of increasing incompetence in either the deep veins only (P = 0.214) or in the combined deep and superficial veins (P = 0.111) with increasing severity of the telangiectasia. There was a statistically significant trend for increasing incompetence in (a) the superficial veins (P = 0.006) and (b) either the superficial or deep veins (P < 0.001) to be associated with advancing grade of telangiectasia. When stratified by gender, significant trends were maintained for male superficial vein incompetence and for either superficial or deep incompetence in both genders. Examination of incompetence in individual venous segments showed that increasing severity of telangiectasia was significantly associated with an increasing proportion of reflux in the upper and lower great saphenous and femoral vein segments. There was no significant association between small saphenous incompetence and increasing grade of telangiectasia. CONCLUSION: There is a significant, but not wholly consistent, association between grade of telangiectasia and reflux in both the deep and superficial systems. This association does not apply to the small saphenous system.