The haemodynamic role of calf perforators under physiological and pathological conditions continues to be a controversial issue. According to the prevailing opinion, calf perforators in healthy people are competent, enable only one-way flow from superficial into deep veins and hinder escape of venous blood from deep into superficial veins, while under pathological conditions these perforators widen, become incompetent and make outward flow possible, induce venous hypertension and create preconditions for the development of chronic venous insufficiency and leg ulcers. In this review paper the evidence is presented, including the results of studies utilising direct venous pressure measurements, plethysmographic findings and electromagnetic flow measurements, that actually an outward flow through calf perforators should not be interpreted as reflux, does not cause ambulatory venous hypertension and that bidirectional flow through these perforators is found not only in pathological conditions but also in healthy people. Calf perforators enable free pressure transmission between the deep and superficial veins, enable flow in both directions, and make deep and superficial veins of the lower leg conjoined vessels. The genuine venous reflux within calf perforators is an inward and not outward flow.