Background: In patients with chronic venous disease (CVD) the number of venous valves and the degree of valve deterioration have not been extensively investigated and are poorly understood. The aim of this prospective study was to quantitatively and qualitatively investigate the venous valves in CVD patients in view of their clinical classification. Patients and methods: Within two years a consecutive series of 152 patients (223 limbs) undergoing primary surgery for great saphenous vein varicose veins was investigated. In all patients the ‘C’ class according to the basic CEAP-classification was registered preoperatively (C2 to C6) for each limb. Both the quantity and quality of venous valves were assessed in the GSV’s after removal. Qualitative evaluation of the valves was based on macroscopic appearance using a classification from 0 to 5 and described as ‘valve disease class’. Results: A negative correlation between age and the number of valves was detected (p = 0.0035). There was an increase of C-class with increasing age. No significant correlation between the average number of valves per meter and the C-class was detected. For all C-classes an average of between four and five valves per meter was counted. Valve disease class was positively correlated with the C-class although the valve disease class was never higher than the C-class (p < 0.05). Conclusions: The valve disease class of the great saphenous vein correlates with the C-class of the CEAP-classification. The number of valves did not correlate with the ‘C’-class. With each increase in the CEAP class the age increased as well.