Over the past year there has been great interest, optimism and anxiety in many societies about developments in the use of embryonic stem cells (ES cells). Within the scientific community there has been debate for some time on the merits and ethical implications of using ES cells. The discussion entered the public domain inthe decisive way during the past year when there were significant changes in legislation governing the use of such cells in Britain and the United States. These changes contributed to the ongoing debate on the ethical and public policy issues involved in this specific area of research and to the broader question on the limits, if any, to be placed on scientific research.