Free radicals were first mentioned by Healey about the hematoma under skin flaps, trying to explain the blood itself has different effect beyond its space-occupying effect or infection. The aim of this study was to determine whether hematoma. would have any effect on neutrophil behavior in muscle flap microcirculation. Rat cremaster muscle flap model was used for measuring intravital different parameters. We used the rat cremaster muscle flap model for direct observation and measurement of rolling and adhesion.