On 1 January 1948, the Common Customs Tariff of the Benelux Union, whose organs had been established in 1946, came into force. In addition, a draft treaty on economic union was negotiated between 1948 and 1950, but it was not signed until 1958. During the first decade of its existence, the Benelux Union was confronted with a large number of technical and political obstacles to the progressive economic integration of the three member countries in order to ensure free internal trade. One aspect considered important at the time was the coordination of statistics. A statistical coordination committee was set up within the Benelux Union in 1947. Decisions on economic integration within the Benelux Union had to be based on coordinated statistics. In addition to these internal difficulties in coordinating Benelux statistics, the three member countries were at the same time confronted with external requirements, linked to the loans for economic reconstruction granted by the IBRD and the conditions demanded under the Marshall Plan in 1947 and 1948. In particular, due to the establishment of the OEEC, the United States demanded that the European states standardize the statistics used to justify the economic reconstruction programmes according to common accounting rules. Within the Benelux Union, cooperation between the three countries was established to ensure coordination of the statistics required by the American authorities at the level of the IBRD, the Marshall Plan and the OEEC. Our contribution examines the political and technical conditions of this coordination of statistics within the Benelux Union, also showing how the choices in the presentation of statistics were politically sensitive. Our contribution is based on an examination of the historical archives of the Benelux Union.