The advent of DNA microarray technology has greatly enhanced our potential to understand the molecular basis of human diseases and to aid in more accurate classification, diagnosis and/or prognosis. This powerful, flexible and highly informative technique has been adopted by many biomedical research disciplines. The use of DNA microarrays for gene expression profiling of patients undergoing organ transplantation has diagnostic and therapeutic potential. By generating global views of the gene expression changes in renal graft function post transplantation, DNA microarray technology will provide important information to improve our understanding of the molecular basis of various causes of graft dysfunction, and therefore suggest improved diagnosis, disease classification, and treatment.