Fumonisins, mycotoxins primarily produced by Fusarium verticillioides and Fusarium proliferatum, occur predominantly in cereal grains, especially in maize. The European Commission asked EFSA for a scientific opinion on the risk to animal health related to fumonisins and their modified and hidden forms in feed. Fumonisin B 1 (FB 1 ), FB 2 and FB 3 are the most common forms of fumonisins in feedstuffs and thus were included in the assessment. FB 1 , FB 2 and FB 3 have the same mode of action and were considered as having similar toxicological profile and potencies. For fumonisins, the EFSA Panel on Contaminants in the Food Chain (CONTAM) identified no-observed-adverse-effect levels (NOAELs) for cattle, pig, poultry (chicken, ducks and turkeys), horse, and lowest-observed-adverseeffect levels (LOAELs) for fish (extrapolated from carp) and rabbits. No reference points could be identified for sheep, goats, dogs, cats and mink. The dietary exposure was estimated on 18,140 feed samples on FB 1-3 representing most of the feed commodities with potential presence of fumonisins. Samples were collected between 2003 and 2016 from 19 different European countries, but most of them from four Member States. To take into account the possible occurrence of hidden forms, an additional factor of 1.6, derived from the literature, was applied to the occurrence data. Modified forms of fumonisins, for which no data were identified concerning both the occurrence and the toxicity, were not included in the assessment. Based on mean exposure estimates, the risk of adverse health effects of feeds containing FB 1-3 was considered very low for ruminants, low for poultry, horse, rabbits, fish and of potential concern for pigs. The same conclusions apply to the sum of FB 1-3 and their hidden forms, except for pigs for which the risk of adverse health effect was considered of concern.Acknowledgements: The CONTAM Panel wishes to acknowledge all European countries and other stakeholder organisations that provided feed consumption data and chemical occurrence data on fumonisins, modified forms and hidden forms in feed.This is an open access article under the terms of the Creative Commons Attribution-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited and no modifications or adaptations are made.The EFSA Journal is a publication of the European Food Safety Authority, an agency of the European Union. Fumonisins in feed www.efsa.europa.eu/efsajournal 2 EFSA Journal 2018;16(5):5242 Fumonisins in feed www.efsa.europa.eu/efsajournal 3 EFSA Journal 2018;16(5):5242Ruminants are considered less sensitive than horses and pigs. Gross and histopathological lesions, as well as changes in serum enzymes and biochemistry indicate an impairment of liver and possibly kidney function. Taking as endpoints the increase in serum enzymes, cholesterol and bilirubin as well as the decrease in lymphocyte blastogenesis a no-observed-adverse-effect level (NOAEL) of (31 mg FB 1-3 /kg feed) could be set only for cattle....