In 2006, researchers at Kyoto University in Japan identified conditions that would allow specialized adult cells to be genetically "reprogrammed" to assume a stem cell-like state. These adult cells, called induced pluripotent stem cells (iPSCs), were reprogrammed to an embryonic stem cell-like state by introducing genes important for maintaining the essential properties of embryonic stem cells (ESCs). Since this initial discovery, researchers have rapidly improved the techniques to generate iPSCs, creating a powerful new way to "de-differentiate" cells whose developmental fates had been previously assumed to be determined. Although much additional research is needed, investigators are beginning to focus on the potential utility of iPSCs as a tool for drug development, modeling of disease, and transplantation medicine. The idea that a patient's tissues could provide him/ her a copious, immune-matched supply of pluripotent cells has captured the imagination of researchers and clinicians worldwide. Furthermore, ethical issues associated with the production of ESCs do not apply to iPSCs, which offer a non-controversial strategy to generate patient-specific stem cell lines.