We analyse, with a simple decision-making model, firstly how the decision-making by consensus was able to be maintained in the GATT negotiations despite of the enlargement of membership to numbers of developing countries and secondly, in the DDA negotiations, why developed country governments lose their interests in concluding the negotiations. We show that the conditions with which the GATT trade negotiations were able to be concluded by consensus despite of the participation of numbers of developing countries are not satisfied any more in the DDA negotiations. The DDA negotiations demonstrates the following dilemma which developed country governments confront in multilateral trade negotiations : a more rigorous application of reciprocity to developing country governments is required to get a maximum benefits from the negotiations for developed country governments, while it limits the coverage of negotiation issues, reduce the level of trade liberalization and increased negotiation costs, all these making the conclusion of the DDA negotiations difficult.