Proteomics has become a major focus as researchers attempt to understand the vast amount of genomic information. Protein complexity makes identifying and understanding gene function inherently difficult. The challenge of studying proteins in a global way is driving the development of new technologies for sys tematic and comprehensive analysis of protein structure and function. Protein expression and purification are hey processes in these studies, but have typically only been applied on a case-by-case basis to proteins of interest. Researchers are addressing the challenge of parallel expression and purification of large numbers of gene products through the principles of high-throughput screening technologies commonly used in pharmaceutical development. Some of the issues relevant to these approaches are discussed here.