Malaria is a potentially fatal infectious disease, considered a serious public health problem in the world, caused by a parasite of the Plasmodium genus. It is transmitted by the bite of the infected female Anopheles mosquito, also after blood transfusions, organ transplantation, sharing contaminated syringes in parenteral drug users, in hospitals, and during pregnancy by vertical transmission. The possibility of diagnosis should be considered in any patient with fever during the stay or return from an endemic area, applying microscopy examination through thick drop and smear, rapid diagnostic tests (RDTs), and molecular diagnostic tests (PCR). Specific treatment is based on the parasite species identified, drug resistance, severity of symptoms, or presence of mixed infection. Treatment is based on oral or intravenous artemisinin and severe forms may require supportive measures and surveillance in intensive care units. This chapter aims to provide knowledge about the dynamics of malarial infection, with emphasis on transmission, diagnostic methods, Plasmodium species, and current treatment regimen.