We have identified three novel members of the DPIV gene family using database mining approaches. Recombinant DP8 shares a post-proline dipeptidyl aminopeptidase activity with the closely related enzymes DPIV and FAP. The similarities between DP8, DP9 and DPIV in tissue expression pattern suggest a potential role for DP8 and DP9 in liver disease, T cell activation and immune function. The role of the two novel enzymes DP8 and DP9 and the other non-enzyme member DPL2 in human disease will be the focus of further studies.