Given the high prevalence of chronic venous diseases (CVD), defining criteria to screen patients who are in need for intervention is attaining primacy. An important clinical criterion for treating CVD is incompetence of larger veins. We have assessed the association of size of afflicted veins with disease severity in patients with CVD to define an acceptable criterion to identify patients who need intervention. Demographic characteristics and risk factors were recorded from 6350 patients. Based on physical examination and venous duplex ultrasound study, patients were classified into clinical severity, etiology, anatomy, and pathophysiology (CEAP) classes and grouped according to the size of the veins which had varicosities. Patients with reflux in smaller veins (vein size <4 mm diameter) were considered as type I and those with varicosities in truncal veins (>4 mm diameter) as type II. Risk ratio was determined by multivariate regression analysis. About 47.67% of patients in this study were found to have CEAP class 3 disease. Compared with varicose veins of large truncal veins, patients with varicosities in smaller superficial veins had 2.85-fold (p < 0.01) more risk of edema and 5.71-fold (p < 0.01) higher prevalence of hyperpigmentation. Varicosities in small superficial veins were associated with higher risk of ulceration (odds ratio 3.93, 95% confidence interval 2.51–6.18) compared with truncal vein reflux. Our study reveals that presence of small varicose veins in patients without truncal saphenous reflux involvement is associated with severe manifestations of venous insufficiency such as edema and skin lesions even in the absence of varicosities in truncal saphenous veins.