The suitability of oats as part of a gluten-free diet is controversial. Contamination of many oats products with wheat, rye and particularly barley, together with inadequacy of available gluten-testing systems may account, at least in part, for the confusion. Some clear evidence has, however, emerged in the past few years that a small number of gluten-sensitive patients display a specific small intestinal T cell response to oat peptides that cannot be explained by contamination with other cereals. Oats could form a potentially useful part of a gluten-free diet, but patients require careful advice and monitoring, backed by robust gluten-assay techniques.