World Health Organization - WHO
National statistics for 50 core indicators on mortality, morbidity, risk factors, service coverage, and health systems, data on chronic diseases and their risk factors for all WHO Member States, as well as statistics for infectious diseases at country, regional, and global levels.
http://www.who.int/

United Nations Statistics Division - Millennium Development Goals
Official data, definitions, methodologies and sources to measure progress towards the Millennium Development Goals.
http://unstats.un.org/