Infectious diseases remain a key cause of morbidity and mortality in the Tropics. Many of these diseases are already preventable by effective vaccines. The Extended Program of Immunization provides protection against six serious infections. However, this program is still not optimally implemented in all developing countries. The Extended Program of Immunization could benefit from the addition of several vaccines, but unfortunately the cost is prohibitive in many areas of the Tropics. For some of the most important infections, such as malaria and HIV, vaccines are not yet available. Novel strategies for vaccine development and policy implementation offer the best hope to combat the infections targeted by the World Health Organization as causing the highest annual death toll worldwide.