This paper reports on the progress in the research and development of the set of patient safety indicators developed by the Health Care Quality Indicators project. The indicators presented here have been recommended by an expert group for further consideration in international reporting on the quality of care on the key dimension of safety. The indicators have been selected by expert consensus, undergone validity testing and have been tested for comparability. While concern remains related to differences in coding and reporting from administrative hospital databases, the rigour with which the indicator work has been undertaken has resulted in the improved ability of countries to report on the quality of care. The work on the development of the patient safety indicators highlights the technical progress made in constructing measures and the ongoing need for methodological improvements. The indicators reported here should not be considered as making inferences on the state of patient safety in countries, but are intended to raise questions towards improving understanding of the reported differences.