In food, molds produce metabolites called the mycotoxins that are hazardous to public health. Together with their toxic and adverse effects on public health; they also bring economic burden on the population. Mycotoxins have carcinogenic, teratogenic, and mutagenic effects; furthermore they cause several toxic effects such as hepatotoxicity, nephrotoxicity, immune system disorders, growth retardation, and dysfunction in reproductive system. Investigations are performed to diminish their harmful effects and to prevent the formation of these toxins which cause a cardinal problem in the developing countries and the whole world. There are physical techniques, natural or synthetic chemicals and biologic methods that are used to prevent harmful effects and risks that originate from mycotoxins as well as prevention of their occurrence. In the present review, current literature related to major toxic effects of primary mycotoxins, degradations, prevention of the occurrence and decreasing of their harmful effects are summarized.