Microcirculation is defined as the blood circulation in arterioles (< 300 um), capillaries and venules. Some authors also included the lymphatic vessels and the interstitium. Although microcirculation contains only about 5% of the total blood volume, it fulfills vital functions as metabolic exchange, homeostasis of interstitial fluids, regulation of blood pressure and thermoregulation.Surveys showed that 57 to 80 % of leg ulcer patients have venous disease, 10 to 25% have Doppler-verified arterial disease (ankle-arm index < 0.9), 10-15% have co-existing rheumatoid disease and 5-12% have concomitant diabetes. About 15% of diabetic patients develop lower limb ulcer. Overlap of various causes may also occur. This study was done on 17 patients having diabetic ulcers, 12 having ischaemic ulcers, 12 having venous ulcers, 6 having collagen ulcers and 9 having traumatic ulcers. Also 10 diabetic patients with no ulcers and 10 normal healthy adult control group were also included.In all of them full non-invasive macro and microcirculatory studies were performed.Our results revealed that diabetics, in general, had lower mean microcirculatory flow as detected by Laser Doppler. The reserve capacity (% change after thermal stimulation) was impaired. The ability of endothelium to deliver O2 to adjacent tissues (e.g. skin) is impaired. These findings were exaggerated by the presence of ulcer (diabetics having ulcers).It is evident from our study that diabetics have in vivo measurable impaired endothelial function compared to control. A sub-population of these diabetics had more endothelial dysfunction and hence were more prone to ulceration. This subgroup of diabetic patients had more neurological affection possibly resulting from severer endothelial dysfunction.One probable explanation is that a more severe type of endothelial dysfunction causes ulceration and neuropathy in these patients.Regarding venous ulceration, they maintain the average resting flow (absence of inherited endothelial dysfunction). However, oxygenation of tissues was affected possibly resulting from severe congestion.Ischaemic ulcerations had lower flow, lower oxygenation and lower reserve capacity caused by acquired diminish flow from proximal large vessel.Collagen diseases caused diminish flow skin microcirculation as well as diminish oxygenation possibly caused by severe acquired endothelial dysfunction resulting from immune complex deposition and / or inflammatory reaction.