The authors studied the changes of Evan blues(EB) of brain tissues and concentration of cytosolic free calcium ([Ca2+]i), and relationship between them and water content of brain tissues following freezing brain edema in rats, to elucidate mechanism and type of brain edema induced by freezing injury. The results indicated that there were close positive relationship between water content and EB of brain tissues, and between [Ca2+]i and water content. We found that not only cytotoxic brain edema(intracellular edema) occurred but also occurred vasogenic brain edema(extracellular edema) followed by blood brain barrier breakdown after brain edema. Freezing brain edema is mixed brain edema.