Jiménez comes from a very political family. His father was Minister of Health under President Salvador Allende, and his sister Mónica Jiménez is the current Minister of Education. He is a physician graduated from the Universidad Catolica de Chile in 1968, who has worked as General Practitioner (1968–1971), trained as Pediatrician in the University of Chile (1971–1974). Practiced and taught Pediatrics, Neonatology and Respiratory Diseases in Children between 1974 and 1990. Trained in Public Health at Johns Hopkins University (1987–1988) where he obtained a MPH in the Hubert Humphrey Program of the US Government.

He was a very active health promoter communicator in mass media (TV, journals, and magazines) in maternal and child health matters in the seventies in Chile, field in which WHO awarded him a Fellowship in 1977. During the 1980s he started doing research in Health Policy at Corporación de Promoción Universitaria (CPU) an NGO, where he developed the Alternative Health Policy for the restoration of democracy in Chile with funding from IDRC and Adenauer Foundation, when he became Minister of Health in 1990 through 1992. In between he consulted in Public Health with the World Bank, Inter-American Development Bank, The Rockefeller Foundation, USAID, WHO and PAHO, among other institutions.

As Minister of Health (1990–1992), Jiménez was the head of a totally new and active team for the Chilean Health Reform Process, in which he was the recognized leader and inspirator of a group of more than 100 Chilean experts from all professions. The Chilean Health Reform process has been acknowledge to be one of the most original and successful of the 1990s with an impact in other policy development institutions such as World Bank, IDB and WHO/PAHO. In 1992-1993, he participated in three consulting meetings for the preparation of the World Development Report (WDR) of the World Bank, with the direct Writers and consultants, in his condition of Minister of Health of Chile.

He was Ambassador to Italy (1995–1998) during the period of Mr. Romano Prodi as Prime Minister, with whom he developed a close relationship. During the same years he was part of the Health in Development Commission of WHO (1994–1997). During this period, he participated in several International Health meetings on a variety of issues related to Health Research for Development. He was nominated Visiting Fellow at the Imperial College School of Management in 1999, and Visiting Professor of International Health at Universita Bocconi of Milano in 2001.

Since 1998, Jiménez has been working as Professor and Researcher in Public Health at the Catholic University where he has been devoted to promote Health Policy issues from an academic point of view, via publications and seminars with students, politicians and PH experts. He evaluated two important Rockefeller Foundation programs (National Epidemiology Boards in 1993 and INCLEN, 1999). Since 2001 he has been the Director of a research project to promote the use of DRG's in clinical management in Chilean hospitals, financed by CONICYT, the National Commission for Scientific Research. His main interest nowadays is Health Policy Research and Promotion in Chile and elsewhere, Research lines are Policy Evaluation of the last 20 years in Chile, especially in successful areas such as Child Survival Second Stage, Renovation of Clinical Management and other policy issues. In Chile he has been permanent advisor in Health Reform to the MoH (2002–2005), and member of the Boards in Nutrition, Vaccines and International Health.

Between the years 2000 and 2001, he participated in the Macroeconomics and Health Commission, led by Professor Jeffrey Sachs in the Working Group 5 on Mechanisms for Improving health outcomes of the poor, under the leadership of Professor Anne Mills. In this period he participated also as Professor in the Summer School of Dubrovnic organized by the European Health Systems Observatory, sponsored by EU, WHO, the World Bank and other institutions. During 2003 he participated and collaborated with Professor Richard Feacham in the design and search for executives at the Global Fund to Fight AIDS, Tuberculosis and Malaria, in which Professor Feacham is Executive Director.

In the field of International Health his main strength is his wide range of contacts around the world in different institutions and fora, gathered in his almost twenty years of activity. His last intervention was as Advisor to the MoH of Turkey in the implementation of Family Medicine model for PHC. During 2005 he started a Global Health Program at Universidad Católica in a joint agreement with MoH and WHO/PAHO.