A prospective study was performed to compare the diagnostic potential of color-coded duplex sonography (CCDS) and that of ascending pressure phlebography (APP) in 61 patients before venous stripping. Varicosis of the long saphenous vein was correctly diagnosed and graded by CCDS in 87% of cases, and varicosis of the short saphenous vein in 97%. CCDS was inaccurate in 3 of 4 cases of recurrent varicosis of the long saphenous vein. Anterior femoral cutaneous varicosis (n = 3), mild postthrombotic syndrome (n = 1) and variant venous anatomy (n = 1) were not diagnosed on CCDS. One Baker cyst was diagnosed by CCDS. In the assessment of venous reflux CCDS seems to be superior to APP. Our results suggest that CCDS is a valuable diagnostic tool for routine imaging before venous stripping. However, patients with ambiguous or inconclusive CCDS results (eg. recurrent varicosis, venous variants) should be examined by APP.