Myasthenia gravis (MG) produces long term disability and affects health-related quality of life (HRQoL). This paper reports the relationship between HRQoL and disability in a group of patients with MG. Adult patients with MG were consecutively enrolled at the Neurological Institute "Carlo Besta". The World Health Organization Disability Assessment Schedule II (WHO-DAS II) and the Medical Outcome Survey 36-Item Short-Form Health Survey (SF-36) were employed, and non-parametric analysis (Spearman's rank correlation and Mann-Whitney U test) performed. One hundred and two consecutive adult patients with MG (70 female; mean age 47.2, sd 15.7) were recruited. The majority of WHO-DAS II and SF-36 scales were significantly correlated; WHO-DAS II summary score correlated better with SF-36 Physical Composite Score (PCS), than with mental composite score (MCS). Significant differences are also reported between patients with different muscle involvement in PCS and WHO-DAS II scores, while no difference was observed in MCS. The impact of MG on disability and HRQoL increases consistently with the disease's severity. Our study highlights that measurements of HRQoL and disability in patients with MG are correlated and sensitive enough to capture different clinical profiles' features. They measure different clinical and psychosocial facets, therefore we recommend employing specific assessments both for quality of life and disability in public health and clinical research on myasthenia gravis.