Mycotoxins are secondary metabolites of fungi that grow on a variety of substrates. Due to their high consumptionof cereals and their sensitivity, pigs are highly impacted by the presence of mycotoxins. At the European level,regulations and recommendations exist for several mycotoxins in pig feed. Among these toxins, fumonisin B1 (FB1),and deoxynivalenol (DON) have a great impact on the intestine and the immune system. Indeed, the intestine isthe first barrier to food contaminants and can be exposed to high concentrations of mycotoxins upon ingestion ofcontaminated feed. FB1 and DON alter the intestinal barrier, impair the immune response, reduce feed intake andweight gain. Their presence in feed increases the translocation of bacteria; mycotoxins can also impair the immuneresponse and enhance the susceptibility to infectious diseases. In conclusion, because of their effect on theintestine, FB1 and DON are a major threat to pig health, welfare and performance.