This study deals with the assessment of quality of life and its main clinical and demographical determinants in a clinical series of 103 patients with multiple sclerosis (MS) (37 men; 66 women; mean age 44.89 years; mean disease duration 12.40 years; mean EDSS score 4.07). We used the MSQOL-54 inventory, a disease-specific instrument recently validated in an Italian population. Each patient underwent a complete clinical assessment, including that of disability status (Expanded Disability Status Scale), cognitive function (Mini Mental State Examination), depression (Hamilton Rating Scale for Depression) and fatigue (Fatigue Severity Scale). In terms of Pearson's correlations, there was a moderate inverse relationship between disability level and the MSQOL-54 physical composite score, and a moderate to strong inverse correlation between depression or fatigue severity and both the physical and mental composite scores. In a stepwise linear regression analysis, depression, fatigue and disability level were confirmed to be significant and independent predictors of quality of life. Quality of life instruments can help to provide a broader measure of the disease impact and to develop a care program tailored to the patient's needs.