The discipline of renal transplantation has been fortunate in having one of the largest and most complete databases of any field of medical inquiry. Many analyses have been performed utilizing these databases and a wide array of views regarding the role and limitations of these analyses exists. In this manuscript, we hope to present the merits and limitations of large database analysis in renal transplantation. In addition, we will attempt to go over the major databases' structures and the critical issues of coding, verification and clinical awareness that help maintain the integrity of this type of analysis. Other fundamental issues that will be covered include the relationship of single center and randomized prospective studies with database analyses, statistical considerations, and hidden selection bias inherent in registry analysis. We hope to present both a guide to investigators who are first embarking on large-scale database analysis and also to present a fair view of the utility and limitations of a potentially very useful research tool in renal transplantation.