Nanotechnology will allegedly have a revolutionary impact in a wide range of fields, but has also created novel concerns about health, safety and the environment (HSE). Nanotechnology regulation has nevertheless lagged behind nanotechnology development. In 2004 the International Organization for Standardization established a technical committee for producing nanotechnology standards for terminology, measurements, HSE issues and product specifications. These standards are meant to play a role in nanotechnology development, as well as in national and international nanotechnology regulation, and will therefore have (...) consequences for consumers, workers and the environment. This paper gives an overview of the work in the technical committee on nanotechnology and discusses some challenges with regard to legitimacy in such work. The paper focuses particularly on stakeholder involvement and the potential problems of scientific robustness when standardising in such early stages of the scientific development. The intention of the paper is to raise some important issues rather than to draw strong conclusions. However, the paper will be concluded with some suggestions for improving legitimacy in the TC 229 and a call for increased public awareness about standardisation in the field of nanotechnology. (shrink)