Multiple sclerosis (MS) is an autoimmune inflammatory illness that affects the central nervous system (CNS) when the body's immune system attacks its tissue. It is characterized by demyelination and varying degrees of axonal loss. This article has compiled various studies elaborating MS and other autoimmune diseases (ADs) co-occurrence. Several conditions that fall into this category, including type 1 diabetes (T1D), rheumatoid arthritis (RA), Guillain-Barre syndrome (GBS), myasthenia gravis (MG), and many others, are found in MS patients and their relatives, suggesting one or more common etiologic mechanisms, including genetic, environmental, and immunological factors, supporting the concept of a possible influence of poly-autoimmunity on MS and the rest of ADs, as well as providing a significant feature for early detection of the disease and also a potential treatment option by clinical neurologists.