The minor Histocompatibility Knowledge Database contains an interactive overview of the identified minor Histocompatibility antigens. It includes peptide sequences, restriction elements, tissue distribution, references to epidemiological studies, and protein/DNA sequences. One can quickly analyse the relevant minor H antigen (mis)matches in HLA matched patient/donor settings. In addition, entering the complete minor and major Histocompatibility typing results provides information on whether minor Histocompatibility antigen mismatches might result in Host-versus-Graft or Graft-versus-Host responses.