The association between cognitive impairment, health-related quality of life (HRQoL) and vocational status has been studied in recent years in cross-sectional studies in multiple sclerosis (MS), but longitudinal data are still lacking. This study assesses this association in a sample of 65 newly diagnosed MS patients followed longitudinally. Each patient underwent a standardised clinical assessment, cognitive tests and the HRQoL SEP-59 questionnaire six months after the MS diagnosis (baseline) and seven years later (y7).Vocational status was also established at baseline and at y7 in MS patients. The HRQoL at baseline was severely reduced in MS patients compared with healthy subjects. The independent predictors for HRQoL composite scores at y7 were the baseline depression score and the memory Z-score. Accordingly, 81.5 % of MS patients worked at baseline and only 54.4 % worked at y7. Among the MS patients who did not work at y7, 72.7 % of them were cognitively impaired, while 27.3 % were unimpaired at baseline. The vocational status at y7 was significantly associated with the baseline IPS Z-score, EDSS and age. Vocational status at y7 and its change over 7 years was significantly associated with cognitive deterioration. IPS or memory dysfunction in the early stages of MS is correlated with a decreased level in health perception, independent of fatigue, depression and physical disability. Cognitive impairment at the diagnosis of MS increases the risk of changing vocational status in MS patients seven years later.