Abstract: Identifying environmental or artificial chemicals as causes of obesity is a new idea or new finding on the etiology of obesity. This idea showed that some environmental pollutants or artificially synthesized chemicals were recognized as important causes of obesity or promoting the tendency of obesity, and were collectively named as obesogens. Now, some chemicals or therapeutic drugs have been confirmed as chemical obesogens, including bisphenol A, diethylstilbestrol, perfluoroalkyl acid (PFOA), organic chlorine, organic tin, and phthalate. The underlying mechanisms of the action of obesogens were disrupting lipid homeostasis and the storage of fat, changing the set-point of metabolic system, and finally promoting the accumulation of adipose tissue. However, owing to the universal existence of chemical obesogens in the environment of our daily life, and the exposure to these chemicals could not be completely avoided, minimizing the opportunities and levels of being exposed to these chemicals might be the best way to prevent the development of obesity.