In a three-country model, this paper investigates linkages between merger incentives of exporting firms and the trade policy of an importing country. When exporting firms come from only one country, the tariff response of the importing country reverses the welfare effects of a merger in the exporting country. If there exist two exporting countries, a merger creates two types of conflicting international externalities. First, a merger in one exporting country increases profits of all firms. Secondly, non-merged firms lose if the importing country is free to raise its tariff in response to a merger of foreign exporters. Copyright � 2006 The Authors; Journal compilation � 2006 Blackwell Publishing Ltd.