This study was designed to evaluate the effect of poor suture technique in microsurgical small-vessel anastomosis on tissue microcirculation. Eighteen male Sprague-Dawley rats were divided into three groups of six animals each: sham control group, regular suture group (control), and inverting suture group. In the regular suture group, a standard single-stitch suture technique was used for microsurgical reanastomosis of the transected common iliac artery. In the inverting suture group, a suture technique was applied inverting the vessel wall, thus simulating poor suture technique. After 24 h, intravital microcirculatory measurements were obtained in the cremaster muscle flap. The inverting suture caused a significant drop in capillary perfusion from 6.40 (sham control) and 5.65 (regular suture) to 1.81 capillaries per visual field (P < 0.005). A poor microsurgical anastomosis may result in a significant reduction of peripheral tissue perfusion, although blood flow through the main feeding vessel is maintained.