The article describes results of food contamination by molds and conditions fostering mycotoxin contamination of foods. The molds growth leads to quality deterioration or spoiling of different kind of foodstuffs. It may result in an unpleasant odour and appearance of the product, reduced seed germination, mycotoxin pollution and/or human allergy and infection. The highly toxic fungal metabolites are particulary dangerous for consumers. Mycotoxins formation in foodstuffs takes place only as a result of growth of toxin-creating molds. Substrates composition influences specially the mold spectrum in foods. Whereas the mold growth and expansion are considerably determined by aw, temperature, pH, atmosphere and microbial competition.