Objectives: To calculate the dynamic stiffness index (DSI) of 18 different brands of medical elastic compression stockings (MECS). Methods: In all, 18 different brands of MECS that were divided into five categories (class IT round-knitted, class 11 flat-knitted, class III round-knitted, class III flat-knitted and class IV flat-knitted MECS) were tested. The static pressure and dynamic pressure pulsations at the B1 level were measured with a newly developed dynamic pressure-determining device. The DSI was calculated. Results: The DSI of all 18 brands of MECS showed higher values compared with the static stiffness. A wide range of dynamic stiffness indices was observed not only between all brands of MECS, but also within the five categories. Conclusions: The DSI of MECS is independent of the compression class and the type of knit. The variation in the DSIs between MECS is not because of any measurement error and would indicate that different therapeutic effectiveness may be expected within one compression class. Therefore, a refinement in the current classification system for MECS with other characteristics such as the DSI is warranted.