Whipple's disease is a rare, chronic infection caused by Tropheryma whipplei, an ubiquitary gram positive bacterium. The disease is associated with a high mortality in absence of an antibiotic treatment. The disease can be detected in affected tissues and body fluids by light and electron microscopy, as well as by polymerase chain reaction (PCR). Musculoskeletal symptoms such as arthralgia and arthritis frequently represent the first manifestation of this multi-system disease; typical subsequent symptoms are weight loss, diarrhea, and abdominal pain. Symptoms of central nervous system involvement are present in 10-40% of cases. We report on a 67 year-old male with a history of migratory oligoarthritis over three decades in whom the causative agent was detected by PCR in synovial fluid only. This case illustrates that searches for the characteristic PAS-positive macrophages and PCR in biopsies from the duodenum may be insufficient and that diagnostic efforts should be complemented with PCR assays from affected tissues or body fluids. It is recommended that antibiotic treatment be carried out with an agent that penetrates well into the cerebrospinal fluid, e.g. ceftriaxone, followed by cotrimoxazole. Antibiotics should be maintained over several months to years. It is prudent to document the disappearance of the pathogen in the affected compartments prior to the discontinuation of the antibiotic therapy.