Since the end of the Cold War, the defense industry in the U.S. has experienced a massive wave of mergers and acquisitions. The number of contractors in many defense sectors decreased significantly in the course of the restructuring in the post-Cold-War era. In light of this observation, it is important to examine whether the "degree of market concentration" in the industry has actually increased with the reduction in the number of contractors. The analysis with the Department of Defense prrocurement data, obtained from the Directorate of Information Operations and Reports for the last five-year period (FY94-FY98), shows that the degree of market concentration in terms of procurement dollars has shown no compelling changes in two sizeable high-technology sectors: the aircraft industry and the missile industry. This suggests that the underlying pressures of scale economies, with soaring R&D costs in the sophisticated modern weapons systems, had played significant roles in restructureing the high-technology defense industries long before the Clinton Administration initiated its policy direction toward consolidation.