A safe health care system requires applying procedures and practices that have demonstrated effectiveness in reducing errors, faults and adverse events in health care, but it also needs to update its knowledge on the factors that contribute to improve patient safety. Adverse events and patient safety are two sides of the same coin, clinical risk. We must ensure that the priority of health managers and providers is aimed at patient safety more than adverse events. They are some fundamental areas of research in patient safety: to estimate the magnitude and features of the clinical risk, to understand the factors contributing to the appearance of adverse events, to evaluate the impact of adverse events on health care system and to identify effective, feasible and sustainable solutions to achieve a safe health care. Key points of patient safety research projects are: aims of research, priority, data and information quality, available resources and methodology. The study of the patient safety and adverse events needs two complementary perspectives: a collective one, based on epidemiological methods and aimed at quantifying the risks in healthcare, and an individual one, based on qualitative methods, to analyze causes and factors contributing to adverse events. Several things are required to improve the patient safety research: better data and information systems, greater collaboration in training between developed and transitional countries, and wider dissemination of experiences and results of the projects. Key points of patient safety research projects are: aims of research, priority, data and information quality, available resources and methodology. The study of the patient safety and adverse events needs two complementary perspectives: a collective, based on epidemiological method and guided to quantifying the risks of healthcare, and another individual, based on qualitative methods, to analyze causes and contributing factors of adverse events. To improve the patient safety research are necessary: better data and information systems, bigger collaboration between developed and transitional countries training and wide dissemination of experiences and results of the projects.