Objective: To evaluate the satisfaction level of multiple sclerosis (MS) patients treated with interferon beta-1b (IFN beta-1b, Betaferon*) using a newly developed application system compared to their currently used application system. Methods: A survey was conducted in Portugal in patients treated with IFN beta-1b for relapsing-remitting MS with the Betaject or Betaject Lite autoinjector. Nurses demonstrated the new application system and supervised the first injection. Patients rated their overall satisfaction retrospectively with their current application system and prospectively after the first, the seventh and the 15th injection with the newly developed application system. Additionally, the ease of use was evaluated for both application systems using a questionnaire consisting of 13 questions. Responses were compiled and descriptive analyses performed. Results: A total of 249 patients evaluated the current and the new system after the first, 235 after the seventh and 174 after the 15th injection. The satisfaction level was high with the current system (70.3%, 'satisfied' or 'very satisfied'). However, compared with the current system, more patients were either 'satisfied' or 'very satisfied' (98%) with the new system after first injection. Only a minority of patients rated 'somewhat satisfied': 2.0% after the first, 8.6% after the seventh, and 4.4% after the 15th injection. Increased overall satisfaction level ('satisfied' or 'very satisfied') with the newly developed system was maintained over time (98% - first, 90.5% - seventh, 93.8% - 15th injection). The thinner, pre-attached 30-gauge needle and the visual signalling of injection completion were among the changes considered as strong improvements to the new system by up to 80.3% of patients. Limitation: Retrospective analysis of current system. Conclusions: This survey documented patient satisfaction with different application systems of IFN beta-1b. The increased satisfaction with the new application system indicates an improvement to the currently used injection system, which may contribute to further advancement in adherence and consequently higher clinical efficacy of treatment.