Health-related quality of life (HRQoL) questionnaires finding increasing use in medicine, but still only few publications have reported on HRQoL in patients with multiple sclerosis (MS). Because of its progressive and disabling nature, the disease has a considerable effect on HRQoL. To facilitate the interpretation of scores for the heterogeneous MS population, we explored differences between subgroups of MS out-patients (n = 90) on two HRQoL instruments: the Medical Outcome Study Short Form-36 and the Disability and Impact Profile. Three disease-related characteristics were studied: severity of MS, time since diagnosis, and MS progression in the past 6 months. The results show that each of these have an effect on one or more aspects of HRQoL. Thus, the longer the disease duration and the more severe and progressive the MS, the lower is the patient's experienced HRQoL.