In the next decade, there will be a concerted effort to develop hypersonic aircraft for commercial applications. It is anticipated that the design of these vehicles will place new demands on material performance at elevated temperatures. Temperatures in excess of 3200° F will be experienced at hypersonic speeds in certain critical areas of the structure, such as the tip of the nose and the wing leading edges. Carbon-carbon composites are one of the few structural materials available which retain a significant fraction of their specific stiffness and strength at elevated temperatures. Consequently, there is a great deal of interest in carbon-carbon composites as structural materials for hypersonic applications. While this material offers much promise for the future, many problems remain to be solved before it can be effectively utilized.