The 'Comprehensive assessment of hazardous effects of engineered nanomaterials on the immune system' (Nanommune) project is assessing the potential of engineered nanomaterials (ENs) to adversely affect the human immune system. The 3-year project brings together 10 partner institutes in the EU and the United States focusing on procurement, synthesis and detailed physicochemical characterisation of various EN categories. The immune system is designed to respond to threats in the form of pathogens or foreign agents. With this in mind, Nanommune is working to show that recognition or non-recognition of ENs by immune-competent cells is a determining factor in their distribution and harmful effects. A multidisciplinary approach is in place to monitor these potential hazards and determine nanotoxic profiles of ENs. The end goal is to create a base of read-out systems for predicting the toxic potential of ENs. To date, a management office has been set up and a project website launched. Kick-off and consortium meetings have also been held. Various articles have been published, including one review in the Annual Review of Pharmacology and Toxicology. In the first 18 months, and after establishing various standard operating procedures (SOPs), activities concentrated on material synthesis and characterisation and in vitro assessments of ENs. So far, researchers have studied the nanomaterials of 15 systems, allowing partner institutions to make good progress in enhancing knowledge of how macrophages can be alerted to or recognise nanomaterials. Macrophages act as sensors that detect a threat and initiate a relevant immune response such as inflammation or elimination. Results from one set of studies show promise for having carbon nanotubes actually degrade in the biological environment. The scientists also showed that nanotubes are recognisable by macrophages. Other studies have made headway regarding the development of materials for drug delivery and other biomedical applications. The Nanommune project's goal of elucidating the hazardous effects of ENs on the immune system will ultimately deliver reliable and sound assessments of the risks to human health that these materials pose. Results are set to benefit public health, researchers and industry.