Approximately 9 million nuclear cardiology studies performed each year in the U.S. use technetium-99m, which is produced from the decay of molybdenum-99. The fragility of the worldwide technetium-99m supply chain has been underscored by current shortages caused by an unplanned shutdown of Europe's largest reactor. The majority of the U.S. supply derives from a reactor in Canada that is nearing the end of its lifespan and whose planned replacements have been cancelled recently. In this article, the clinical importance of technetium-99m and our tenuous dependence on the foreign supply of molybdenum are addressed, along with potential measures that may be taken to ensure that America's supply chain remains unbroken.