Background Attention disturbances are frequently observed in multiple sclerosis (MS) patients. The aim of this study was to provide new evidence regarding the suitability of using self-reported QoL information in this impaired population by exploring the construct validity, reliability, and external validity of a MS-specific quality of life (QoL) instrument. Methods Design: cross-sectional study. Inclusion criteria: MS patients of any disease subtype. Data collection: sociodemographic (age, gender, marital status, education level, and occupational activity) and clinical data (Expanded Disability Status Scale, disease duration); QoL (MusiQoL and SF36); and attention performance (Wechsler Memory Scale and PASAT). According to the French norms, non-impaired and impaired populations were defined. For each population, suitability indices were provided to quantify how the structures matched with the initial structure of the reference population assessed in the validation study. Findings One hundred and twenty-four consecutive patients were enrolled. The factor analysis performed in the impaired populations showed that the questionnaire structure adequately matched the initial structure of the MusiQoL. The unidimensionality of the dimensions was preserved, and the internal/external validity indices were close to those of the reference population. Conclusions Our study suggests that attention impairment dysfunction did not compromise the reliability and validity of the self-reported QoL questionnaires.