OBJECTIVE: We aimed to evaluate the effect of slow-release (SR) Fampridine on multiple outcome measures reflecting different domains, and to compare the responsiveness of the Six Spot Step Test (SSST) and the Timed 25 Foot Walk (T25FW). METHODS: For this study 108 participants were included. On day 0 they were tested with the T25FW, the SSST, the 9-Hole Peg Test (9-HPT), the 5 Times Sit-To-Stand test (5-STS) and the Symbol Digit Modalities Test (SDMT). Four weeks of treatment with SR Fampridine 10 mg BID was commenced. Participants were tested again after 26-28 days of treatment. RESULTS: Mean changes observed were: SSST -3.4±6.4s (p<0.001), T25FW -1.2±3.7s (p<0.001), 9-HPT -1.2±6.0s (p<0.001), 5- STS -3.4±7.2s (p<0.001) and SDMT 1.4±4.8 a.u. (p=0.003). Change on the SSST differed significantly from T25FW (SSST 17.0±19.6% vs. T25FW 11.2±17.1%, p=0.0013). Some 48.6% were found to have a meaningful change on the SSST compared with 25.7% on the T25FW. The response to treatment with SR Fampridine did not correlate with age, sex, Expanded Disability Status Scale and disease duration. CONCLUSION: SR Fampridine treatment has significant effects on different domains including upper and lower body and cognition. Furthermore, the SSST is more responsive to the effect of SR Fampridine than is the T25FW. ClinicalTrials.gov identifier: NCT01656148.