Dorijan Marušič was born on 13 June 1957 in Koper, where he attended primary and secondary school. After graduating from Gimnazija Koper, he enrolled at the University of Ljubljana, Faculty of Natural Sciences and Engineering, in 1976, graduating in mathematics in 1981. Soon afterwards he became a medical student at the Faculty of Medicine in Ljubljana, graduating in 1989. He specialised in internal medicine and was trained at Izola General Hospital, University Clinic in Groningen and University Medical Centre in Ljubljana. He concluded his specialist training in 1995.

Between 1991 and 1998, Dr Marušič attended numerous advanced education and training programmes in the field of internal medicine. In the period from 1998 to 2000, he was the head of the intensive therapy unit at Izola General Hospital, and in May 2002, went on to assume the position of medical director. In December 2000, he was appointed State Secretary at the Ministry of Health of the Republic of Slovenia and re-appointed to the same position in 2004. In 2003, he enrolled in post-graduate studies in management of non-profit organisations at the Faculty of Social Sciences, University of Ljubljana. Prior to his nomination for Minister of Health, he was an adviser to the Director-General of the Health Insurance Institute of the Republic of Slovenia and engaged in a clinic as a specialist in cardiology.

Dr Marušič is the author or co-author of more than 200 scientific works published in professional journals and collections. He has also published over 350 popular articles. He has lectured and participated in a number of conferences and expert meetings. Dr Marušič heads the Coronary Society of Slovenian Istria and is the vice-president of the expert council of the Association of Coronary Societies and Clubs of Slovenia. He is a member of the Slovenian Society for Emergency Medicine, the Slovenian Society of Anaesthesiology and Intensive Care Medicine, and the Slovenian Society of Cardiology.

On 7 April 2010, Health Minister Marušič took the oath of office before the National Assembly.