A case of Whipple's disease with central nervous system (CNS) involvement has been retrospectively diagnosed. At the age of 50 and after six years of recurrent bouts of pyrexia, anorexia and loss of weight, a man developed a subacute encephalitis. Two episodes of acute loss of vision were followed by changes in mental status, supranuclear ophthalmoplegia and oculo-facio-cervical myorhythmias which remained present until death, one year later. Combined light- and electron microscopic studies have demonstrated: No. 1 the presence in the CNS of nodules containing large amounts of Sieracki cells; No. 2 the existence of bacteria in various stages of degeneration in macrophages or in the neuropile. A review of CNS complications in Whipple's disease is made.