Abstract Introduction The Expanded Disability Status Scale (EDSS) is usually calculated through a neurological examination with self-reported performance. This may lead to incorrect assessment of Functional System scores (FSs). Aim of our study was to estimate the difference between EDSS obtained during routine visits, or after specific tests. Methods We enrolled 670 MS patients that underwent a regular neurology consultation, and visual evaluation using optotype tables, ambulation evaluation with a rodometer, and cognitive assessment with the Brief International Cognitive assessment for MS (BICAMS). We calculated a new integrated EDSS (iEDSS) using the refined values of the FS and compared it to the standard EDSS. Results Visual, cerebral and ambulation FSs were significantly higher compared with the self-reported counterpart [+ 1.169 (95%CI 1.077, 1.262; p < 0.001), + 0.727 (95%CI 0.653, 0.801; p < 0.001) and + 0.822 (95%CI 0.705, 0.939; p < 0.001), respectively]. Mean iEDSS was higher than EDSS (+ 0.642; p < 0.001). Visual acuity tests worsened the EDSS in 31% of cases, cognitive tests in 10%, ambulation measurement in 35%, all three measurements in 59% of cases. Conclusions Objective measurement of FSs results in a more accurate EDSS score in almost two-thirds of cases. This could lead to a more thorough evaluation of patients in the transition or progressive phase.