The ability to culture human stem cells long term, and possibly indefinitely, and to control how such cells specialise to form the different tissues of the body offers the possibility of major advances in healthcare. Stem cells have been isolated and cultured, but a great deal of research is required to develop cell lines which can generate replacement cells and tissues to treat many diseases.Stem cells have arisen in policy debates and a lack of universal agreement on their use, safety and morality suggests these debates will become more widespread and impassioned. Issues that have arisen with the evolution of stem cells include patient safety, the exploitation of desperate patients, and distribution of resources. Developing science and growing hype warrant ethical scrutiny to ensure the nonmaleficence of patients and a balance between patient safety and scientific progress. A conservative approach combining domestic control with international regulation is recommended to simultaneously monitor and foster the promising, but perilous world of stem cells.