Mycotoxins were reviewed. The general characteristics of mycotoxins were discussed. Mycotoxins can be regarded as toxic metabolites produced by a wide variety of fungi. The greatest problem for humans comes from mycotoxins that commonly contaminate foodstuffs and from eating poisonous species (mushrooms). Mycotoxins present in foodstuffs represent a more serious problem than mushroom poisoning because they may be present in basic staples, even in the absence of any visible mold growth, and are normally detectable only by chemical methods. Mycotoxins may develop on live crop plants or can be produced during storage. Methods for detecting and analyzing mycotoxins were summarized. The toxicity of mycotoxins was discussed. Mycotoxins show a wide range of toxicity. Most human and animal exposures to mycotoxins result from ingesting contaminated foodstuffs. Mycotoxins have also shown immunomodulatory effects. Aflatoxin-B1 (1162658) has been shown to inhibit DNA synthesis in lymphocytes, natural killer cell activity, and generation of concanavalin-A stimulated suppressor cells in mice. Specific mycotoxicoses caused by mycotoxins were discussed, including aflatoxicosis, ergotism, mycotoxic nephropathy, trichotheosis, and yellowed rice toxicosis. Important mycotoxins not associated with causing mycotoxicoses in humans such as gliotoxin, sporidesium, and patulinin were described. Controlling and preventing mycotoxicoses were discussed.