Disturbances of the central thermoregulation in patients with multiple sclerosis (MS) are not often reported. We describe a 45-year old patient with a 13-year history of MS, who developed a clinical picture of recurrent hyperthermia. MRI showed a bilateral involvement of the hypothalamus in the setting of diffuse white matter disease. Serial body temperature measurement for five consecutive months disclosed an inversion of the circadian temperature rhythm. The clinical presentation and MRI findings suggested abnormalities of the central thermal control in relation to MS widespread involvement of the central nervous system (CNS).