Abstract
This paper examines some features of evolution and results for airline deregulation and open-sky policy in the United States. This focuses on the interaction between the domestic policy and the international policy and impact of these policies on airline markets. The dominance by major airlines in oligopoly markets have continued. The dominance raises constrains for fair competitiveness and provides the importance of competition policy applied for dominant conducts as well as airline market structure. In international airline markets, open-sky policy and strategic alliances led by U.S. have caused some changes of international airline regime. Under the liberalized markets, competition policy and anti-trust immunity have become important issues.