See http://unstats.un.org/unsd/methods/m49/m49regin.htm Dear Yves, There is no US government mandate or instructions on how to group world regions. This is what I have ascertained about how to divide up the world into regions. 1. The Clinical Trials.gov method – I spoke with them yesterday. The organization of the map is a bit arbitrary. How they group countries depends on whether there are studies being conducted in a given geographical area, political and other not so clear reasons. She did not know why Mexico was grouped with Canada and the US. Additionally, not all regions of the world are on their map; i.e. Melanesia, Polynesia, Micronesia 2. United Nations has standard country codes and geographical regions for their statistical use that is widely used in the public sector. The macro geographical regions are arranged, to the extent possible, according to continents and assigns countries to only one macro-geographical region. These assignment of countries or areas to specific groupings was created for their statistical convenience. This listing contains most, if not all, countries in the world. UN website: http://unstats.un.org/unsd/methods/m49/m49.htm 3. Come up with a system that works for the study. Have a look at the INSIGHT web page - http://insight.ccbr.umn.edu/ My Ideas: 1. I would not use clinicaltrials.gov regions, since there is a good chance that it may change and has some peculiar groupings. 2. I would use the UN continental regions or some modification of it since they have a very comprehensive country list with reasonable geographical assignments. Mexico is in Central America; Turkey is in Western Asia; Russia is in Eastern Europe (not North Asia???). 3. Then the DCC will know what region to put it in since they have such a nice Geographical Listing (abridged) http://unstats.un.org/unsd/methods/m49/m49regin.htm with all the countries assigned to a region, also attached as a PDF. Below is one I put together, as an example. The numbers are the UN country/regions codes, see attached list for the specific countries. The 019 Americas level could be divided in Northern America and Latin America as in the UN classification. 002 Africa 014 Eastern Africa 017 Middle Africa 015 Northern Africa 018 Southern Africa 011 Western Africa 019 Americas 003 North America b 021 Northern America – this includes Canada, US, Greenland, Bermuda, Saint Pierre and Miquelon 013 Central America 029 Caribbean 005 South America 142 Asia 143 Central Asia 030 Eastern Asia 034 Southern Asia 035 South-Eastern Asia 145 Western Asia 150 Europe 151 Eastern Europe 154 Northern Europe 039 Southern Europe 155 Western Europe 009 Oceania 053 Australia and New Zealand 054 Melanesia 057 Micronesia 061 Polynesia Let me know if you have any questions. Ruth Clinical Trials Specialist NHLBI, DCVs, ACAD 6701 Rockledge Drive, MSC 7956 Bethesda, MD 20892 Phone: 301 435-0401 Fax: 301 480-1336 kirbyr@nhlbi.nih.gov