Background: Sudden visual loss is one of the emergent problems that may be a sign of a life-threatening disease. It should be quickly evaluated to identify the treatable causes. Case report: A young man without any history of certain disease was referred to the emergency department with complaint of sudden blindness. He was presented with fever, coriza symptoms and progressive blurring of vision which ultimately led to his visual loss. After carefully evaluation, finally suspected diagnosis of acute fulminant multiple sclerosis was made. Discussion: Multiple sclerosis is a chronic inflammatory disease that is associated with acute attacks of neurological dysfunction. Some of these attacks are an emergent situation and need to early detection and treatment. There is a variant of multiple sclerosis that called acute fulminant multiple sclerosis which can cause sudden visual loss.