This analysis draws upon a variety of sources to provide a tally of the number of patients receiving organ replacement therapies and the costs associated with the provision of such therapies. Constituent data were available from treatment-specific patient registries, peer reviewed reports in scientific literature, business publications, and industry sources. The magnitude and economic scope of the contemporary organ replacement enterprise were found to be much larger than is generally recognized. In the year 2000, the lives of over 20 million patients will be sustained, supported, or significantly improved by functional organ replacement. The impacted population grows at over 10% per year. Worldwide, first year and follow-up costs of organ prosthesis exceeds $300 billion US dollars per year and represents between 7 and 8% of total worldwide health care spending. Remarkably, in the United States, the costs of therapies enabled by organ replacement technology exceed 1% of the Gross Domestic Product. These findings constitute an incontestable tribute to the scientific significance and medical impact of the still nascent field of substitutive medicine. At the same time, the enormous magnitude of resources dedicated to organ replacement raises several issues related to overall cost effectiveness of current modalities and raises challenges and opportunities for future technical developments.