The European Commission (EC) and the Scientific Committee on Emerging Newly Identified Health Risks (SCENIHR) have begun a public consultation on the preliminary opinion concerning “Guidance on the Determination of Potential Health Effects of Nanomaterials Used in Medical Devices.” The aim of the opinion is to address the use of nanomaterials in medical devices and to provide information for risk assessors regarding specific aspects that need to be considered in the safety evaluation of nanomaterials. Guidance is provided on physico-chemical characterization of nanomaterials, the determination of hazards associated with the use of nanomaterials, and risk assessment for the use of nanomaterials in medical devices. The safety evaluation of nanomaterials used in medical devices is discussed in the context of the general framework for biological evaluation of medical devices as described in the International Organization for Standardization (ISO) 10993-30 1:2009 standard. Therefore, the risk assessment is performed taking into consideration type of device, type of tissue contact, and the duration of contact, thus identifying the specific exposure scenario. The Guidance is intended to provide information to help with safety evaluation and risk assessment of the use of nanomaterials in medical devices that should be considered in conjunction with the ISO 10993-1:2009 standard. The Guidance highlights the need for special considerations in relation to the safety evaluation of nanomaterials in view of the possible distinct properties, interactions, and/or effects that may differ from conventional forms of the same materials. For the risk evaluation of the use of nanomaterials in medical devices, a phased approach is recommended based on potential release and characteristics of the nanomaterials. SCENIHR is seeking comments on the risk assessment related to the Guidance. Comments are due October 3, 2014.