This chapter discusses synthetic insecticides. It reviews public health pesticides, covering topics such as common terms and concepts in medical entomology to introduce the diverse relationships among humans, arthropods, and disease pathogens; the historical and current impact of arthropods on human health; the basic concepts of vector management; a brief list of noninsecticidal alternatives; the classification schemes and general properties of public health pesticides and repellents; and specific examples of pesticides in vector management, particularly mosquito control. The spectacular success of synthetic insecticides in the decade immediately following World War II generated widespread enthusiasm that the major scourges of humankind, such as yellow fever, malaria, and typhus, could be conquered. However, these short-term successes resulted in major increases in disease transmission primarily due to resistance in both the arthropod to insecticides and to drugs by the pathogen. The result of these failures has forced the public health community to reevaluate strategies and has resulted in the development of evidence-based management or integrated disease management. Employing this management strategy, both insecticides and drugs are used in a targeted manner that results in a significant increase in efficacy, environmental safety, and cost-effectiveness.