Projecting renal replacement therapy–specific end-stage renal disease prevalence using registry data. End-stage renal disease incidence and prevalence are increasing in many countries worldwide. Projections of ESRD prevalence are useful for forecasting future resource requirements, and organ failure registry databases are valuable for the development of appropriate projection models. We outline one method of generating renal replacement therapy (RRT)–specific ESRD prevalence projections based on data obtained from the Canadian Organ Replacement Register (CORR). To illustrate the methods, we present national RRT-specific prevalence projections for Canada to the year 2005. Continued large increases in ESRD incidence and prevalence are projected, particularly among diabetics. As of December 31, 1996, there were 17,807 patients receiving RRT in Canada. This number is projected to climb to 32,952 by the end of 2005, for a relative increase of 85% (average relative increase of 5.8% per year). Registry data are a useful basis for future health care planning.