The objective of the present study was to show if the pressure values of compression stockings indicated by the producers correspond to the actual pressure in vivo. This study compared pressure and stiffness of ready-made stockings (Venosan) of different classes measured on the leg and by laboratory testing. This experimental study was conducted in the textile laboratory of a company that manufactures compression stockings. Twelve legs from healthy volunteers were fitted with ready-made calf-length compression stockings of the European classes I, II, and III. In addition, two class I stockings were applied over each other. The in vivo interface pressure was measured using the medical stocking tester (MST) in position B1, eight centimeters proximal to the inner ankle. Stiffness was defined as an increase of pressure due to enhanced stretch that reflects the elastic property of the textile and was assessed by measuring the difference of interface pressure between standing and supine positions at B1. In the laboratory, MST was used to check the pressure of these stockings on wooden leg models. Then circular slices were cut out from the stockings at the B1 level and stretched by a Zwick dynamometer in the transverse direction. Force/extension curves were plotted, from which the pressure and stiffness of each individual stocking were calculated. The pressure profile measured in four positions along the leg by MST showed a degressive gradient on the wooden model but not on the human leg due to the measuring geometry in the ankle region. Pressure values on the leg corresponded to the in vitro measurements calculated from the force/extension curve with a bias (difference of the means) of - 2.1 and 4.1 mm Hg. In 95% of the subjects, the difference was between - 10.1 and 5.8 mm Hg (Bland-Altman plot). The correlation between in vivo and in vitro measurements was highly significant (p<0.0001), Spearman correlation coefficient; r=0.8161). In vitro and in vivo measurements showed an increase of stiffness with increasing compression class. The highest value were found for two class I stockings applied over each other. Conclusion. Pressure and stiffness measured in vivo, correlate well with the laboratory findings and should be used in future studies, especially when different compression devices are to be compared.