In this review, we have provided an overview of the environmental risk factors for attention deficit hyperactivity disorder (ADHD), focusing on the major environmental toxicants related to the disorder. Researchers have indicated that since the characteristics of ADHD are complex, the disorder’s etiology involves multiple genes of moderate effect interacting with environmental factors. The possible roles of prenatal and perinatal exposure have been the main focus of research on environmental risk factors for ADHD. Among environmental toxicants, we reviewed the potential effects on the development of ADHD of exposure to lead, nicotine, alcohol, polychlorinated biphenyls (PCBs), and dioxin. Further, for the each neurotoxicant, clinical prevention or intervention strategies aimed at reducing a child’s risk from environmental toxic insults have been presented.