Systematic applications of four tactics are essential to planning and carrying out disease and injury prevention in field and combat operations. Listed in order, they are applicable for prevention of malaria (or any other threat): 1) Determine disease and injury threats in the area of operation before deployment. 2) Identify or develop countermeasures to reduce threats to an acceptable level. 3) Educate personnel regarding threats and train in correct use of countermeasures. 4) Command enforcement of countermeasures. The next three sections of this chapter review effective malaria countermeasures available. Preventive countermeasures are divided into three sections: Personal Protective Measures, Chemoprophylaxis, and Unit Protective Measures. Medical personnel must seek information to answer the questions outlined below and determine which countermeasures to employ, and make recommendations for the same to commanders.