T-2 toxin is the most toxic trichothecene mycotoxin, and it exerts potent toxic effects, including immunotoxicity, neurotoxicity, and reproductive toxicity. Recently, several novel metabolites, including 3′,4′-dihydroxy-T-2 toxin and 4′,4′-dihydroxy-T-2 toxin, have been uncovered. The enzymes CYP3A4 and carboxylesterase contribute to T-2 toxin metabolism, with 3′-hydroxy-T-2 toxin and HT-2 toxin as the corresponding primary products. Modified forms of T-2 toxin, including T-2-3-glucoside, exert their immunotoxic effects by signaling through JAK/STAT but not MAPK. T-2-3-glucoside results from hydrolyzation of the corresponding parent mycotoxin and other metabolites by the intestinal microbiota, which leads to enhanced toxicity. Increasing evidence has shown that autophagy, hypoxia-inducible factors, and exosomes are involved in T-2 toxin-induced immunotoxicity. Autophagy promotes the immunosuppression induced by T-2 toxin, and a complex crosstalk between apoptosis and autophagy exists. Very recently, "immune evasion" activity was reported to be associated with this toxin; this activity is initiated inside cells and allows pathogens to escape the host immune response. Moreover, T-2 toxin has the potential to trigger hypoxia in cells, which is related to activation of hypoxia-inducible factor and the release of exosomes, leading to immunotoxicity. Based on the data from a series of human exposure studies, free T-2 toxin, HT-2 toxin, and HT-2-4-glucuronide should be considered human T-2 toxin biomarkers in the urine. The present review focuses on novel findings related to the metabolism, immunotoxicity, and human exposure assessment of T-2 toxin and its modified forms. In particular, the immunotoxicity mechanisms of T-2 toxin and the toxicity mechanism of its modified form, as well as human T-2 toxin biomarkers, are discussed. This work will contribute to an improved understanding of the immunotoxicity mechanism of T-2 toxin and its modified forms. Keywords T-2 toxin • Modified T-2 toxin • Metabolism • Immunotoxicity • Human exposure assessments • Biomarkers Abbreviations AhR Aryl hydrocarbon receptor AKNA AT-hook transcriptionfactor Akt Serine/threonine protein kinase ARE Antioxidant response element CREB CAMP-response clement-binding protein CYP450 Cytochrome P450 DAS Diacetoxyscirpenol DRP-1 Dynamin-related protein 1 DON Deoxynivalenol D3G Deoxynivalenol-3-glucoside ECM Extracellular matrix EIF2AK2 Double-stranded RNA-activated protein kinase ERK Etracellular signaling kinase FXR Farnesoid X receptor GH Growth hormone Qinghua Wu and Zihui Qin contributed equally to this work.