This study we compare the duplex-derived parameters of reflux in patients with early and advanced superficial venous insufficiency (SVI) to identify parameters reflecting this. Two thousand and one hundred sixty limbs with primary reflux, categorized according to the CEAP (clinical, etiologic, anatomic and pathophysiologic) classification, and the patients were divided into two groups (group I [C1-3, Ep, As, Pr]; group II [C4-6, Ep, As, Pr]) were studied. The vein diameter, reflux duration(s), mean reflux velocity (MRV; cm/s), peak reflux velocity (PRV; cm/s), and total reflux volume (TRV; ml/s) were determined at the sapheno-femoral junction (SFJ), great saphenous vein (GSV) and sapheno-popliteal junction (SPJ). Age and the proportion of males were greater in group II. MRV, PRV and TRV were greater in group II at the SFJ, SPJ and in GSV (p <0.01 for all), although the duration of SPJ reflux was non-discriminatory (p = 0.78). From receiver operating characteristic (ROC) curve, optimal cut-off points of 27.8, 47.8, and 36.2 cm/s for the PRV at the SFJ (p <0.01), GSV (p <0.01), and SPJ (p <0.01) discriminated between the two groups. PRV and MRV improved discrimination between early and advanced SVI compared to reflux duration.