Introduction: Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common chronic mental disorders diagnosed in children. There is clear evidence that some environmental factors such as the exposure of mother to chemicals during pregnancy, premature birth, environmental toxins, and various diseases such as bacterial diseases and encephalitis are strongly associated with ADHD. The aim of this study is to investigate the environmental factors influencing the development of ADHD from the toxicology perspective. Materials and Methods: In this review article, we searched the relevant articles up to June 2023 in various databases, including PubMed, Scopus, Web of Science, and Google Scholar, using relevant keywords. We included all articles that related to the influencing factors in the review process. Results: The investigation showed that various toxic factors such as smoking, alcohol, pesticides, bisphenol A, mycotoxins, phthalates, heavy metals, and food additives have an effect in causing ADHD, and in the case of many toxins, the results of different studies are contradictory. Conclusion: This review shows an important role for some of the investigated pollutants in increasing the risk of ADHD symptoms. These factors can affect neurodevelopmental processes and neurotransmitter systems, and contribute to ADHD symptoms. It is not possible to draw firm conclusions about the relationship between certain chemicals and ADHD,and therefore more research is required to find stronger evidence of the relationship or lack of relationship between exposure to certain chemicals and this disorder.