Common disability scales in multiple sclerosis (MS) are often weighted towards physical disability. Non-motor symptoms such as depression, fatigue and pain substantially influence wellbeing in MS. Health-related quality of life (HRQoL) measures the broader impact of MS and might indicate less obvious disease burdens. We analysed HRQoL, using the Nottingham Health Profile Part I (NHP-I), among 345 secondary progressive MS (SPMS) patients participating in a randomized trial of interferon-beta1a (IFN-beta1a), 22 mug subcutaneously weekly, or matching placebo. The results did not reveal any beneficial effect of IFN-beta1a in any outcome measure. NHP-I sub- and sum scores were compared for 217 population controls and correlated with demographic and clinical disease variables. SPMS patients had lower NHP-I sum and all subscores than the controls. Patients experiencing disease progression reported worse NHP-I sum scores. Increased fatigue, Expanded Disability Status Scale (EDSS) and Arm Index scores were independently associated with reduction in several NHP-I subscores. SPMS patients had significantly lower HRQoL than controls and physical disability (EDSS and Arm Index), disease progression and fatigue strongly influenced this. MS.