Deoxynivalenol (DON) is the most abundant trichothecene in food and feed. It causes both acute and chronic disorders of the human and animal intestine, liver and the immune system. The structural basis for the toxicity of DON has not been fully elucidated. Using the pig as a target and a model species for human, the toxicity of DON and its deepoxy-metabolite (DOM-1) were compared. Animals were exposed by gavage to 1 and 0.5 nmol toxin/kg bw./day for two and three weeks respectively. Whatever the dose/duration, DOM-1 was less toxic than DON in terms of weight gain and emesis. In the three week experiment, animals were vaccinated with ovalbumin, and their immune response was analyzed in addition to tissue morphology, biochemistry and hematology. DON impaired the morphology of the jejunum and the ileum, reduced villi height, decreased Ecadherin expression and modified the intestinal expression of cytokine. Similarly, DON induced hepatotoxicity as indicated by the lesion score and the blood biochemistry. By contrast, DOM-1 only induced minimal intestinal toxicity and did not trigger hepatotoxicity. As far as the immune response was concerned, the effects of ingesting DOM-1 were similar to those caused by DON, as measured by histopathology of lymphoid organs, PCNA expression and the specific antibody responses. Taken together, these data demonstrated that DOM-1, a microbial detoxification product of DON, was not toxic in the sensitive pig model but retained some immunemodulatory properties of DON, especially its ability to stimulate a specific antibody response during a vaccination protocol.