Individuals from industrialized nations frequently travel to countries with malaria, so health care providers need to be familiar with current recommendations for prevention of malaria. Changes in drug susceptibility of malaria parasites and evolving knowledge of how well drugs are tolerated necessitate periodic review of guidelines for prophylaxis of malaria, especially of chloroquine-resistant Plasmodium falciparum malaria. Mefloquine is the drug of choice for chemoprophylaxis for most travelers, with doxycycline and chloroquine being less effective alternatives. Mefloquine is well tolerated at prophylactic dosages, but anecdotal reports have raised concerns about its adverse effects. Resistance to this drug has emerged in parts of Southeast Asia and may spread to other regions of the world. The major disadvantages of doxycycline are the need for daily dosing, its contraindication for young children and pregnant women, and its adverse effects. Chloroquine is effective for prophylaxis only in Central America, the Caribbean, and parts of the Middle East. Few new drugs will be available in the near future because of reduced funding for antimalarial drug research and development; therefore, the usefulness of currently available drugs needs to be prolonged by rational use. Increased efforts should be made to ensure that alternative drugs will be available for prevention of malaria.