An ad hoc committee of the National Academies of Sciences, Engineering, and Medicine will conduct a study to assess the long-term health effects that might result from the use of antimalarial drugs by adults, in particular mefloquine, for the prophylaxis of malaria. The committee will examine the currently available medications, as approved by Food and Drug Administration and/or used by the Department of Defense, and of interest to the Department of Veterans Affairs, and the long-term health effects that might occur in any organ system. These include latent effects that might be expected from their use by Service members during deployment to areas with endemic malaria, such as Afghanistan. Special attention will be given to possible long-term neurologic effects, long-term psychiatric effects and the potential development of Posttraumatic Stress Disorder (PTSD). Additionally, the committee will consider approaches for identifying short-term, long-term, and persistent adverse health effects of antimalarials. The committee will develop findings and conclusions based on its review of the evidence; the report will not include recommendations.