In three treated patients with a generalized invasion by a tumor of the lymphoid-hemopoietic systems, the neuropathologic findings were consistent with Wernicke's encephalopathy. The clinical picture was atypical, but thiamine deficiency by severe malabsorption was the probable cause of this neurologic complication. It is postulated that the chronic form of Wernicke's encephalopathy must occur more frequently than previously shown in treated and long-standing cases of such kinds of tumors.