Given the importance of coal in world energy supply an analysis of the relevant geographic market is essential for consumers, producers, as well as for competition policy. The purpose of this paper is to define the relevant economic market for steam and coking coal, and to test the hypothesis of single world markets for these coal products. Methodologically the paper relies on two different tests for defining markets, using both shipments data and price data. The results from both methods point in the same direction. In the case of coking coal the results indicate that the market is essentially global in scope, and also that the market has become more integrated over time. The results for steam coal show that the market is more regional in scope, and there exist no clear tendencies of increased integration over time. One policy implication of the finding that the steam coal market is more regional in scope, and thus that the market boundary is smaller than if the market would have been international, is that a merger and acquisition in this market likely would have been of a more concern for antitrust authorities than the same activity on the coking coal market. (c) 2004 Elsevier Ltd. All rights reserved.