One strategy for business seeking to improve their competitive position today is to achieve efficiency through mergers. In recent years, worldwide mergers have achieved records high and antitrust enforcement authorities are facing new challenges involving high-technology industries. Merger regulation is one of the most important elements of competition policy of in all country. The objective of merger regulation is to assist in the maintenance of competitive markets. However it is recognized that mergers have both benefits and costs. Mergers may enable improvements in productive efficiency but the cost of increased potential for the firms in the market to exercise individual or coordinated tnarket power. There has been considerable debate in many countries as to how the best measure and weigh these costs and benefits and much of this debate has occurred in the context of the appropriate merger test - substantiai lessening of the competition or dominance. Merger analysis should consider a wide range of efficiencies should be a function of their magnitude and probability, the degree to which they will enable the merged firm to be a better competitor and thereby enhance (or not lessen) competition for the benefit of consumers, and the delay with which such consumer benefits are to be realized. Since efficiencies evidence typically resides with the merging parties and is difficult to corroborate, the merging parties should produce credible evidence of any claimed efficiencies and their likely pro-competitive effects. The rapid rate of tnarketplace change is causing some firms or industries to fall on hard times. One response of firms buffeted by changing market condition is to merge, sometimes with a stronger competitor. When faced with mergers involving firms is distressed industries or near-failing firms, antitrust should assess such transactions in terms of their likely competitive effects. Therefore merger-guidelines are critically needed by Indonesia to empower the Komisi Pengawas Persaingan Usaha (KPPU - the Fair Trade Commission) to enforce the Competition law