Tissue pH measurements in patients with peripheral vascular disease can provide an indication of tissue perfusion and metabolic status in areas affected by ischaemia. Using micro-electrodes which have been specially developed to measure tissue pH in the skin (pHs) it is possible to show a pHgradient along the lower limb in patients with severe ischaemia, which can be reversed by successful surgical treatment. The vasoactive drug naftidrofuryl has been shown to have properties which can improve oxidative metabolism within ischaemic cells without necessarily causing any haemodynamic alterations. These properties may be beneficial in patients with peripheral vascular disease. The micro-electrode method of pHs measurement was used to assess the effects of conservative management in patients with severe lower limb ischaemia due to peripheral vascular disease. Forty patients were randomly allocated into two groups who received either conventional conservative treatment done, or conservative treatment plus naftidrofuryl (both intravenous and oral) for 7 days. pHs recordings were made before and after treatment in 40 patients. No statistically significant change in pHs values could be found when the two treatment groups were compared overall. However; in patients with vest pain alone it was possible to define a highly significant (pC0.01) change in pHs vahes in the ischaemicparts of the limb after 7-days'treatment with naftidrofuryl, but not in the group who did not receive the drug. In cases with established ischaemic skin changes no significant changes in pHs were found in either treatment group.