Whipple's disease, a multisystem chronic granulomatous disease treatable by antibiotics, usually presents clinically with gastrointestinal or joint symptoms. Usually, the diagnosis is substantiated by small intestinal biopsy. This shows diastase-resistant periodic-acid-Schiff-(PAS)-positive inclusions in the cytoplasm of macrophages within the lamina propria. By electron microscopy, this PAS-positive material consists of 1.5 X 0.2-mum bacilli and fine fibrillar material within macrophage phagolysosomes. Rarely, Whipple's disease presents clinically as a primary neurologic disease without gastrointestinal symptoms. Because untreated cerebral Whipple's disease usually progresses rapidly to death, it is imperative to establish the diagnosis promptly. This report describes a case of cerebral Whipple's disease without gastrointestinal symptoms that was diagnosed early by light-and electron-microscopic study of brain biopsy material.