Summary: Carbon and nitrogen isotope analyses were performed on human and animal bones recovered from pits within Danebury Iron Age hillfort. All results are within the range expected for European Holocene specimens and are similar to those from other Iron Age sites in central southern Britain. Our results indicate that the human diet included a significant amount of animal protein (meat and/or dairy products) consumed on a regular basis, but do not preclude a diet based heavily on cereal consumption. In comparison with the extensive heterogeneity visible in the animal isotope values, the homogeneity of the human values is rather striking. This may be a reflection of the much slower turnover rate of adult human collagen and may also indicate that the humans consumed a much greater variety of food than the fauna (thus averaging many isotopic sources). This is consistent with the role of hillforts as central places and locations for food distribution and exchange. © 2010 Blackwell Publishing Ltd.