In response to concerns regarding the potential risks to human health from exposure to nanomaterials, the Directorate General for Health and the Directorate General for Labor asked the French Institute for Public Health Surveillance, with scientific support from a multidisciplinary working group convened by the Institute for Public Health Research, to explore the feasibility of establishing a surveillance system for workers potentially exposed to nanomaterials. In response to this request, this report provides an overview of the many uncertainties inherent in this topic, including issues related to definitions, the scope of nanomaterials, the identification of health events that can be monitored, the difficulties in identifying companies and workers potentially affected by nanomaterials, and the challenges posed by the measurement of nano-object aerosols. After examining the various epidemiological surveillance protocols that could be used to study the long-term effects of exposure to nanomaterials, the InVS proposes a two-pronged surveillance system comprising, on the one hand, a prospective cohort study and, on the other hand, repeated cross-sectional surveys. The repeated cross-sectional studies would focus on all nanomaterials, whereas the cohort study would concern only a few nanomaterials considered to be priorities. It is possible to begin registering workers potentially exposed to nanomaterials immediately, which constitutes the initial step of the cohort study. The report concludes with recommendations regarding epidemiological research. (R.A.)