The Fourth Asia Oceania Human Proteome Organisation Membrane Proteomics Initiative (AOHUPO MPI) Workshop took place on 22 June 2008 in Cairns, Australia, with approximately 90 attendees from academia and industry. Participants from ten of the seventeen collaborating centres presented workshop papers. This was part of the pre-conference programme of the Joint Fourth Asian Oceania Human Proteome Organisation Conference and the Second Pacific Rim International Conference on Protein Structure.