Whipple disease is an uncommon chronic bacterial infection due to Tropheryma whipplei. Clinical manifestations are protean (joint pain, fever, weight loss, abdominal pain, lymphadenopathies), and the diagnosis is often delayed. Although previously considered a late manifestation of Whipple disease, neurological involvement is now frequently the initial clinical manifestation and represents the greatest risk for long-term disability. All patients should be treated and monitored as if they had central nervous system disease even if they are asymptomatic. Neurological manifestations include dementia (56 percent), abnormalities of eye movements (33p. cent), involuntary movements (28 percent), seizures, hypothalamic dysfunction, myelopathy, ataxia and psychiatric manifestations. Uveitis, retinitis, optic neuritis and papilloedema may be found. 80 percent of the reported cases of neuro-Whipple had associated systemic symptoms or signs but many patients are presenting without concurrent intestinal manifestation. Thus, the disease may remain undiagnosed or misdiagnosed, as rheumatoid arthritis or sarcoidosis. Traditionally, the diagnostic procedure of choice is biopsy of the duodenal mucosa by demonstrating PAS-positive foamy macrophages. However, not all cases have small bowel infiltration and tissue obtained from sites clinically affected may be helpful. CT and MR images of the central nervous system are normal or not specific: atrophic changes, mass lesions, focal abnormalities and hydrocephalus. The application of a PCR assay against Tropheryma whipplei has transformed the diagnosis. Positive results have been obtained from several tissues and from CSF and PCR is more sensitive than other techniques. All patients must be treated with antibiotics which cross the blood-brain barrier. Most agree that initial treatment with a combination of parenteral penicillin and streptomycin for at least 14 days is appropriate, thereafter cotrimoxazole orally 3 times a day for at least one and probably for two years. Third generation cephalosporins, rifampicin and chloramphenicol have been used successfully. PCR is recognized to be a useful tool for monitoring progress but it is sometimes difficult to reverse established neurological defects.