The global report Hidden cities: unmasking and overcoming health inequities in urban settings is one important component of the overall WHO and UN-HABITAT strategy to strengthen the response of the local, national and global health communities to reduce health inequities in an increasingly urbanized world. The report exposes the extent to which the urban poor suffer disproportionately from a wide range of diseases and health problems, which can be traced back to inequalities in their social and living conditions. It also provides evidence-based information and tools to help municipal and health authorities tackle health inequities in their cities.