Recurrent fevers are defined as multiple stereotypical febrile episodes separated by spontaneous symptom-free intervals and occurring for months and years. Hereditary recurrent fevers are rare prototype Mendelian diseases due to inherited mutations in genes encoding partners of the innate immunity. Recurrent episodes of fever plus acute features of inflammation starting during childhood with family history are the main clues for suspecting HRF. Their common associated complication is AA amyloidosis. The diagnosis is made on clinical grounds but the genetic diagnosis may contribute in most cases of monogenic hereditary recurrent fevers. Recurrent fevers must be distinguished from intermittent fevers, mostly infectious, characterized by variation in associated symptoms from episode-to-episode and without periodicity.