The markets for industrially used biomass for energy purposes are developing rapidly toward being international commodity markets. Determining international traded biomass volumes for energy purposes is difficult, for several reasons, such as challenges regarding the compilation of statistics on the topic. While for some markets (pellets and ethanol) separate overviews exist, no comprehensive statistics and summaries aggregating separate biomass streams are available. The aim of this paper is to summarise trade volumes for various biomasses used for energy and to review the challenges related to measurement of internationally traded volumes of biofuels. international trade of solid and liquid biofuels was estimated to be about 0.9 EJ for 2006. Indirect trade of biofuels thorough trading of industrial roundwood and material byproducts comprises the largest proportion of trading, having a share of about 0.6 EJ. The remaining amount consisted of products that are traded directly for energy purposes, with ethanol, wood pellets, and palm oil being the most important commodities. In 2004-2006, the direct trade of biofuels increased 60%, whereas indirect trade has been almost constant. When compared to current global energy use of biomass (about 50 EJ yr(-1)) and to the long-term theoretical trading potential between the major regions of the world (80-150 EJ yr(-1)), the development of international trade of biomass for energy purposes is in its initial stage, but it is expected to continue to grow rapidly. (C) 2009 Elsevier Ltd. All rights reserved.