Background: Only a few studies have been done focusing on the quality of life (QoL) of patients with multiple sclerosis (MS) as well as their family members. The aim of our research was to determine the factors that influence the QoL of MS patients in advanced stage of disease and their caregivers. Methods: The sample of the cross-sectional study included 153 patients with MS and 74 caregivers. QoL was measured using the PNDQoL questionnaire (Progressive Neurological Diseases Quality of Life), and the severity of illness was assessed through the following scales: EDSS (Expanded Disability Status scale), PPS (Palliative Performance Scale), and ADL (Activity Daily Living). Results: The following predictors of the global QoL of the MS patients were identified - age, EDSS, symptom burden, daily care, emotional functioning, and spiritual_nonreligion functioning (R-2 = 0.569;F= 32.900;p< 0.001). The following predictors of the global QoL of caregivers were identified - age, emotional functioning, spiritual_nonreligion functioning, patient's QoL, and feeling of care (R-2 = 0.431;F= 18.690;p< 0.001). Conclusion: Appropriate intervention should be directed particularly at older patients and caregivers who have faced the disease for longer time and at patients without any partner. Supporting the emotional and social well-being and mitigating the burden caused by symptoms of the patients as well as caregivers can improve the QoL of both groups.