In this review, we compare and contrast two popular models for multiple sclerosis (MS), Theiler's murine encephalomyelitis virus (TMEV) disease and experimental allergic encephalomyelitis (EAE). These models are used to investigate the viral and autoimmune etiology of MS, respectively. Infection with live TMEV is an essential component of TMEV demyelinating disease. TMEV-specific cellular and humoral immunity and apoptosis of infected cells eliminate virus from the gray matter of the central nervous system (CNS) during the acute phase of TMEV disease. In contrast, during the chronic phase, TMEV persistently infects glial cells and/or macrophages in the white matter. During the chronic phase, recruitment of macrophages, TMEV-specific T cells and antibody, with the induction of apoptosis are harmful to the host, leading to inflammation and demyelination. In EAE, induction of encephalitogenic CD4+ T cells is an important component for disease. After stimulation and activation, these T cells upregulate adhesion molecules and are able to enter the CNS. Th1 cytokines augment the recruitment of mononuclear cells in the CNS. Macrophages and/or glial cells secrete cytotoxic factors leading to demyelination in conjunction with B cells secreting anti-myelin antibody. Although immunopathological pathways during the course of the demyelination in TMEV infection and EAE are not always the same, oligodendroglial apoptosis is observed in both models, suggesting that their demyelinating processes share a common terminal pathway and finally lead to quite a similar clinical and pathological picture.