Productivity of construction industry is low especially in waste production. To demonstrate how it can be
better than this situation, we should identify its waste sources. Whereas sources of waste are different for any material, so construction activities across supply chain that use so many kinds of materials have some different sources of waste. For responses to the question "which kind of sources effect on waste production in activities?" 30 questionnaires were distributed between experts. By following question about impact of five top sources on waste in activities, using binominal test, it observed that sources of waste for any activity are same as waste sources of materials that used in that. Indeed a category of sources that had been influenced on waste production of some materials were effective on waste in activities that use them. [Mohamad Reza Parsanejad, Mansor Momeni, Ali Mohaghar. Impact of sources on waste production in activities: A new approach. Nature and Science 2011;9(1):20-28]. (ISSN: 1545-0740). http://www.sciencepub.net.