We have previously shown that the adenosine triphosphate (ATP) content of keloids remains high for a long time. In keloids, anaerobic glycolysis may be related to the production of ATP. In this study, we counted the vessels in keloids, hypertrophic and atrophic scars in a defined area, and measured the cross-sectional areas of their internal lumens immunohistopathologically and the lactate concentrations. The mean number in a defined area was smallest in keloids as was the mean internal area of vessels. The lactate content of keloids was 39.4 (13.5) mmol/g of protein, of red scars 23.8 (7.5), of pink scars 23.8 (7.6), and of white scars 13.3 (7.3). These results indicate that ATP may be produced by anaerobic glycolysis in keloids, and that the decreased and narrowed vessels may reduce oxygen perfusion. The blood supply to keloids is inadequate, and this persists.