Summary: Disease associations provide useful aetiological clues in relation to diseases of unknown causation; this holds particularly for auto‐immune disorders which tend to occur together in individuals and in related family members. Nine patients suffering from both multiple sclerosis and presumed auto‐immune disorder were found from a survey of case records of 326 patients with multiple sclerosis admitted to a large city hospital between 1955 and 1970. There was autoimmune disease affecting the thyroid gland in four cases, the stomach in two and the adrenal gland in one, and there were two cases of rheumatoid arthritis and one of pemphigus vulgaris. Such associations are relevant to the concept of an auto‐immune pathogenesis for multiple sclerosis, but with reservations based on the uncertain prevalence of these diseases in Australia and the ascertainment errors inherent in this type of study.