The natural occurrence of mycotoxins in food and foodstuffs and the fate of mycotoxins during food processing were investigated. Aflatoxins and /or Fusarium mycotoxins(nivalenol, deoxynivalenol and zearalenone) were detected in commercial samples of various foods and foodstuffs collected at Tokyo markets. It was found that the mycotoxins were decomposed at high temperature, but some remained after heating at usual temperatures for an ordinary period for domestic cooking(boiling, deep-frying of grilling). Industrial food manufacturing processes were relatively effective for removing mycotoxins