AN ETHIC SYSTEM OVERVIEW: BRAZILIAN PERSPECTIVES FOR OBSERVATIONAL STUDIES  Background             Observational studies have been one of the hallmarks for the development of public health and health economics fields. It includes epidemiologic studies, evaluation of patterns of care, use of resources, cost of illness, analysis of safety and effectiveness of interventions from real world. However, there are different patterns of requirements for ethics reviews concerning observational studies, including vastly available models of ethics systems among different countries.  Therefore, the objective of this study is to evaluate the ethics system, regulations and guidelines concerning observational studies in the selected countries. Methodology             Guidelines and regulations from Brazil, Argentina, Japan, New Zealand, Australia, USA and UK were reviewed to evaluate the ethics system and available guiding principle for observational studies. Additionally, a literature review was performed in the database Medline and SciELO mesh using the terms "ethics", “observational study” and "multicenter study" among other similar terms. Results             In Brazil, same ethics regulation is applied for both interventional and observational projects, plus there is unsatisfactory ethics review timelines and duplicity of ethics review when considering multicenter studies. Specific pathways for multicenter studies are available only in New Zealand, Australia, USA and UK. For the exception of Brazil, other evaluated countries have specific guidelines, recommendations or regulations for observational studies. Conclusions             Brazil and Argentina still have a lot of challenges to overcome regarding the overall ethics system. Applying same ethics regulations or guidelines from interventional studies may not be the most adequate choice for observational studies.