We determined the validity of water content, rump fat thickness, a subjective fat index, a kidney fat index, and an index based on total body weight (TBW) and the hind foot length (HFL) in order to predict lipid content of arctic foxes Alopex lagopus. The total fat content was either determined by extracting lipid from minced carcasses (N = 75) or by dissecting all visible adipose tissue (N = 35). Water content and rump fat thickness proved to be the best predictors of fat content in arctic foxes. The ratio TBW/HFL was also a reliable index and should be a convenient and practicable way of estimating the condition of live foxes. A subjective fat index could be applied when divided into three categories, whereas the kidney fat index was not a reliable predictor of lipid content of arctic foxes.