The mosquito-transmitted viral infectious disease dengue is a major public health problem in tropical and sub-tropical countries, where it causes dengue fever, dengue haemorrhagic fever and dengue shock syndrome. Almost 400 million people are infected by dengue each year, causing around 20,000 deaths. There are no vaccines or therapeutic regimens currently available for the prevention and treatment of disease. A number of vaccines are under development and several have entered clinical trials while others are still in the pre-clinical phase. Most dengue vaccines in animal models have been found to provide a degree of protective immunity by eliciting neutralizing antibodies against all tested serotypes of the dengue virus, and this forms a foundation for future vaccine design. It is probable that a refined, second generation multivalent vaccine will be required to target each of the five now recognized dengue serotypes.