Division of General Internal Medicine, Gasthuisberg University Hospital, Herestraat 49, B-3000 Leuven, Belgium. daniel.knockaert@uz.kuleuven.ac.be
Recurrent fever of unknown origin is mostly caused by rather rare diseases and many cases remain unexplained. The very limited literature data do not allow one to construct a diagnostic algorithm. A number of general principles should be kept in mind before starting the investigation for this rare subtype of fever of unknown origin.