Membrane proteins perform a wide range of biological functions including respiration, signal transduction and molecular transport. The results of various genome projects have shown that up to 30 % of proteins encoded by eukaryotic cells are membrane proteins. Structural research on membrane proteins is, however, only a partially conquered area; less than 200 independent structures of integral membrane proteins have been reported to date. A more fundamental understanding of the structure-function relationships of membrane proteins will make invaluable contributions to structural biology, pharmacology and medicine. The mission of the MPL is to provide equipment, training and expertise in the area of membrane protein crystallisation and crystallography, to the membrane protein X-ray crystallography community. The MPL will also develop new techniques for crystallisation and structural determination of membrane proteins. This will lead to substantial improvements in the rate at which structures of membrane proteins are solved.