In order to help reconstruct ancient dietary, domestic, and ritual behaviour, a method was developed to identify the blood protein albumin in ancient skeletal material. This was an inhibition enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody of IgG class against human albumin. With fresh material, the technique gave consistent and specific results and could detect as little as 10 ng of albumin. Extracts of bone from the English Civil War (A.D. 1644), Mediaeval (A.D. 1100–1400), Early Saxon (A.D. 450–600), Roman (A.D. 100–200), Iron Age (ca 400 B.C.) and Bronze Age (2200–1700 B.C. cal.) periods were then tested, samples of fresh human and animal bone being included as positive and negative controls, respectively. Albumin was demonstrated in human bone from all periods; there was no evidence of cross-reactivity with animal material. Detection seemed to depend largely on amount of sample and chronological age; other factors, such as physical integrity of the specimen and soil characteristics, appeared to be less important. Preliminary studies of other ancient skeletal remains showed that animal species could be readily identified and that albumin was probably still detectable in cremated material. It is concluded that our method provides a tool specific and sensitive enough for the reliable identification of the speciesorigin of small fragments of bone (and possibly of blood stains) and will thus allow insight into past behaviour patterns. ELISA may also be suitable for identifying other molecules (such as HLA and ABO) which would help determine racial affiliation and disease predisposition among ancient populations.