Angiography was performed on 10 legs of fresh cadavers to investigate the density and orientation of small arteries of the lower leg. It was revealed that there were more vertically arranged arteries than the horizontally arranged ones in the skin and superficial fascia. The entire surface of the lower leg was divided into 9 regions. The density of arteries of different orientations in the skin and fascia was measured regionally. Though the density of different regions had a significant difference, no statistical significant difference was found in vessel anastomosis rate between different regions. Where the density was high, the anastomoses were rich. According to these findings, suggestions for the design of random flaps in the lower leg were discussed.