In this review, the anatomy and physiology of the venous system and its pathophysiology are described. Theories regarding the possible causes of disturbances in venous microangiopathy are summarized. The theories concern the deoxygenation of red blood cells, arteriovenous shunts, fibrin cuffs, and the trapping of growth factors and/or white blood cells. Furthermore, microlymphatic, neurologic and hemorheologic disturbances in venous disease are outlined. Findings in venous microangiopathy obtained from histology, capillary microscopy, microlymphography, laser Doppler fluxmetry and transcutaneous oxygen partial pressure are detailed. Finally, the recently discovered pattern of perfusion in microcirculation within and around venous ulcers is discussed.