Raymund AC Roos became MD in 1977 and defended his PhD thesis in 1984. The topic of his thesis was Nuclear Membrane Indentations in Huntington disease, an electron microscopical study. Initially as head of the outpatient department of the LUMC in Leiden he managed a movement disorder clinic with the focus on Huntington disease (HD). He participated in several clinical trials in HD. Since 1993 as head of the department he focussed on HD only. He was supervisor of 20 HD PhD thesis out of more than 50 PhD students. He has over 200 international publications on HD as (co)author out of 400 and author of several bookchapters. He is since 2004 site-investigator for Registry of the European Huntington Disease Network of the largest site in Europe. From 2014 he is PI of Enroll-HD in Leiden. He is site PI of TRACK-HD, the international collaboration in the search for biomarkers. He is active in the board of the EHDN and secretary general of the research Committee on Huntington disease of the World Federation of Neurology. From 1992 till 2014 he was responsible for the resident training in Leiden and was responsible for the new framework for the residence program in Neurology for the Netherlands: NEURON. In april 2015 the 6th edition of the book Neurology for medical students was published where he was co-director.