Blood samples were collected from a high density population of wild badgers in Woodchester Park, Gloucestershire, England, where animals were routinely captured and examined as part of a long-term ecological study, and a selection of haematological and biochemical variables were measured. The badger cubs had lower red blood cell counts and haemoglobin concentrations than the adults, consistent with physiological anaemia, and lower serum protein concentrations. Growth of muscle and active bone formation in the cubs probably accounted for their higher serum concentrations of creatinine and calcium, and higher activities of alkaline phosphatase. Only triglyceride concentrations varied between the sexes. The serum concentration of urea was higher than observed in other mustelids, consistent with a protein-rich diet and possibly related to the consumption of earthworms.