Structure-based drug discovery has proven useful in improving and shortening the drug development process. The approach of structural genomics to study a large number of targets in parallel has been commonly applied to protein families and even whole genomes. Paradoxically, although membrane proteins represent the largest type of drug targets, up to 70% today, determination of their structure has been modest compared to that of soluble proteins. Because membrane proteins are important for drug discovery an emphasis has been placed on developing technologies and methods to determine membrane protein structures. Several structural genomics initiatives have been established, focusing on the structural biology of membrane proteins.