Neglected diseases are prevalent in less developed countries and are associated with high levels of mortality and/or morbidity. The drugs used in clinical practice are toxic, reducing patient compliance, and generally do not result in a cure, and there has also been a surge in drug resistance. Additionally, a major challenge in drug treatment lies in reaching the intracellular sites infected by parasites. The development of nanotechnology-based drug delivery systems for drugs intended to treat neglected diseases is a promising avenue because the use of nanocarriers presents the ability to target drugs to the infected cells, and the prolonged drug release profile possible with these systems permits longer contact between the drug and the parasite. This review describes the roles of colloidal drug carriers, such as liposomes, polymeric nanoparticles and solid lipid nanoparticles, in research on optimizing the delivery of antileishmanial, antitrypanosomal, antichagasic and antimalarial agents.