Pesticides are chemicals used to destroy, prevent or control pests. According to FIFRA, pesticides are used to prevent or destroy pests. Pests include weeds, diseases, mites and insects. In addition, pests are may be mites, insects, rodents, plants, or any other living thing. Main groups pesticides are insecticides, fungicides, herbicides and rodenticides. Agricultural production has increased 82% about 30 years due to pesticides. After the pesticide incorrect use some damage on environmental (soil, water, bird, fish, bee….) and human health. For example; absorption through the skin is the most common route of poisoning of human. Therefore, we have to some rules such as before the applying the pesticides; read and follow the label carefully, be aware of the people and the environment in and around treated areas etc. In this article will be discussed adverse effects of chemicals.