Introduction: This paper reviews the most important articles using data from the Danish Multiple Sclerosis Registry (DMSR) published in the past 25 years. Research topics: These articles include: descriptive epidemiological studies, indicating that the female incidence of multiple sclerosis (MS) in Denmark has increased considerably; follow-up studies on social events, showing that patients at a high rate lose their working ability and their spouses/partners; mortality studies, demonstrating a considerable excess mortality; cause-of-death studies; comorbidity studies; and, most importantly, historical prospective studies identifying some risk factors (e.g. infectious mononucleosis) and refuting others (head trauma and a number of occupational exposures e.g. nurses, utility workers, people exposed to solvents). The most important results are briefly presented. CONCLUSION: The Danish MS register has proven to be a valuable tool for MS epidemiology and has provided knowledge that could not otherwise be achieved.