Aflatoxins are cancerogenic compounds produced predominantly by certain strains of the Aspergillus genus. The ideal solution for minimization of health risk that aflatoxins pose is the prevention of foods and feeds contamination. Unfortunately, these contaminants can never be completely removed, and on that account, many studies have been carried out to explore an effective process of their detoxification to a threshold level. Biological decontamination seems to be attractive because it works under mild, environmentally friendly conditions. This review is focused on the biological detoxification of aflatoxins, especially aflatoxin B1, by microorganisms. There are briefly mentioned aflatoxin metabolic pathways in the human and animal body. Microorganisms such as soil or water bacteria, fungi, and protozoa and specific enzymes isolated from microbial systems can degrade aflatoxin group members with varied efficiency to less- or nontoxic products. Some aflatoxin-producing fungi from Aspergillus species have the capability to degrade their own synthesized mycotoxins. Yeasts and lactic acid bacteria work as biological adsorbents that prevent aflatoxin's transfer to the intestinal tract of humans and animals. Aflatoxin B1 absorbed into the organism could be metabolized by significantly different pathways. They lead to the production of the relatively nontoxic compounds, on the one hand, or to highly toxic active forms on the other hand.