ISO Guide 64:2008 provides guidance on addressing environmental issues in product standards. It is primarily intended for product standards writers. Its purpose is to outline the relationship between the provisions in product standards and the environmental aspects and impacts of the product, to assist in drafting or revising provisions in product standards in order to reduce potential adverse environmental impacts at different stages of the entire product life-cycle, to emphasize that taking into account environmental issues in product standards is a complex process and requires balancing competing priorities, to recommend the use of life-cycle thinking when defining environmental provisions for a product for which a standard is being drafted, and to promote the future development of relevant sector guides for addressing environmental issues in product standards by standards writers, consistent with the principles and approaches of ISO Guide 64:2008.Whenever a new product standard is drafted or an existing product standard is revised or intended to be revised, the project managers and their technical committee chairman/convenors are encouraged to actively promote the application of this Guide. Furthermore, at any stage in the standard development process, experts are encouraged to include environmental issues in their comments.In order to take account of the diversity of products and their specific environmental impacts, as well as the need for relevant environmental knowledge, it is useful for standards writers to involve environmental experts in the work. The project managers and their technical committee chairman/convenors might wish to take into account other relevant, current sector-specific guidance and environmental provisions identified in related standards.Unless they are closely related with environmental issues, ISO Guide 64:2008 does not address issues of occupational health and safety or consumer safety as separate or specific aspects of the product life cycle. Standards writers can find guidance on these issues in other guides.