Introduction: Multiple sclerosis (MS) generates physical deficits such as muscle weakness of the lower limbs and reduced functional mobility, thus presenting a decline in the patients' quality of life. Objective: Correlate the muscle strength of lower limbs with functional mobility and quality of life in patients with multiple sclerosis. Methodology: Correlational, ex post facto retrospective study. Data from 49 patients with multiple sclerosis were used, chosen from an existing database of the Neurofunctional Physiotherapy Outpatient Clinic of the Hospital de Clínicas de Porto Alegre. The tests analyzed for the study were: The 5-repetition sit-to-stand (STS) test (5STS - lower limb muscle strength) and Timed up And Go (TUG - functional mobility), in addition to the Multiple Sclerosis Impact Scale (MSIS-29 - quality of life) in individuals with MS. Results: The average time that patients performed the 5STS was 15.39 (± 8.65) seconds. In the TUG, the average was 11.50 (± 8.40) seconds. Regarding the MSIS-29 scale, the percentage in the physical domain was 37.83% (± 25.10%) and in the psychological domain 45.18% (± 28.92%). A positive correlation was found between the time to perform the 5STS test and the time to perform the TUG (r=,566 p<,000). A positive correlation was also found between 5STS and the physical domain of MSIS-29 (r=,351 p<,0014). Conclusion: The greater the muscular strength of the lower limbs, the greater the functional mobility and the quality of life in the physical environment of these patients.