Four diagenetic parameters have been chosen to represent the state of diagnesis of bone buried on archaeological sites. They are histological preservation, protein content, crystallinity, and porosity. The authors describe how these parameters are measured and present results from populations of bones from three different sites. The results show the extent and variation of the degree of change both within a site and between sites. In particular, the correlations between diagenetic parameters are examined, that give clues about the processes which cause alteration. The value of porosity determinations (both at the intercrystalline level and at coarser levels) in revealing the degree of diagenetic change in bone, and in underlying the dynamics of the interaction between buried bone and the surrounding water is stressed. The data also indicate (but are too restricted to prove) the following: microbiological attack is generally complete within less than 500 years; substantial levels of protein may remain in bone after maximal micromorphological alteration; loss of protein appears to be independent of other diagenetic change; the correlated loss of microporosity with increase of crystallinity suggests these changes may arise from the dissolution, perhaps with subsequent recrystallization, of the smallest hydroxyapatite crystallites.