Introduction: The aim of our study was to systematically review the growing body of published literature reporting on one specific multiple sclerosis (MS) treatment, fingolimod, in the real world to assess its effectiveness in patients with MS, evaluate methodologies used to investigate MS in clinical practice, and describe the evidence gaps for MS as exemplified by fingolimod. Methods: We conducted a PRISMA-compliant systematic review of the literature (cut-off date: 4 March 2016). Published papers reporting real-world data for fingolimod with regard to clinical outcomes, persistence, adherence, healthcare costs, healthcare resource use, treatment patterns, and patient-reported outcomes that met all the eligibility criteria were included for data extraction and quality assessment. Results and discussion: Based on 34 included studies, this analysis found that fingolimod treatment improved outcomes compared to the period before treatment initiation and was more effective than interferons or glatiramer acetate. However, among studies comparing fingolimod with natalizumab, overall trends were inconsistent: some reported natalizumab to be more effective than fingolimod and others reported similar effectiveness for natalizumab and fingolimod. These studies illustrate the challenges of investigating MS in the real world, including the subjectivity in evaluating some clinical outcomes and the heterogeneity of methodologies used and patient populations investigated, which limit comparisons across studies. Gaps in available real-world evidence for MS are also highlighted, including those relating to patient-reported outcomes, combined clinical outcomes (to measure overall treatment effectiveness), and healthcare costs/resource use. Conclusions: The included studies provide good evidence of the real-world effectiveness of fingolimod and highlight the diversity of methodologies used to assess treatment benefit in clinical practice. Future studies could address the evidence gaps found in the literature and the challenges associated with researching MS when designing real-world studies, assessing data, and comparing evidence across studies. (C) 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).