I would like to review and some empirically tests of the available evidence concerning the question of economies of scale and technical change on the regulated industries, particularly the trunk route airlines and the gas & energy industries, in the U.S. And after estimation, the result should be discussed and compared with the same result of Japan and Australia. Since the regulated industries are considered to have scale economies in the world-wide, governments intervene them in developed and developing countries. In the deregulation stream from the beginning of 80's in the Western countries, many kinds of public utilities and public enterprises have been privatized and deregulated. The performance evaluation of public corporations and regulated industries have taken on a high profile in the climate of micro-economic reform that has prevailed in the recent past. Thus the question of whether or not there are significant scale economies, scope economies and productive efficiency in such public corporations and regulated industries, and international comparison are vital for formulation of appropriate public policy. The cost structure of those (scale economies, scope economies and technical change) should be properly tested.