The classical portrayal of poor health in tropical countries is one of infections and parasites, contrasting with wealthy western countries, where unhealthy diet and behaviours cause non-communicable diseases (NCDs) like heart disease and cancer. Using international mortality data, we show that most NCDs cause more deaths at any age in low- and middle-income tropical countries than in high-income western countries. Causes of NCDs in low- and middle-income countries include poor nutrition and living environment, infections, insufficient regulation of tobacco and alcohol, and under-resourced and inaccessible healthcare. We identify a comprehensive set of actions across health, social, economic and environmental sectors that can confront NCDs in low- and middle-income tropical countries and reduce global health inequalities.