Periodic fevers (fevers that occur predictably at fixed intervals) are unusual in infants and children. The classic periodic fever syndrome is cyclic neutropenia (neutropenia followed by infections and fever that recur every 21 days). A new periodic fever syndrome PFAPA (periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis) has been characterized over the past decade. PFAPA is defined clinically, because specific laboratory abnormalities have not been found. The clinical characteristic of PFAPA is high fevers (usually 40.0 degrees C to 40.6 degrees C) recurring at fixed intervals every 2 to 8 weeks. The fevers last for about 4 days, then resolve spontaneously. Associated with the fevers are aphthous stomatitis in 70% of patients, pharyngitis in 72% of patients, and cervical adenitis in 88% of patients. PFAPA is not familial and begins before the age of 5 years. An episode of PFAPA can be aborted with one or two small doses of prednisone. The episodes of PFAPA may last for years and the patient is well between episodes. The cause of PFAPA is unknown and there are no reported sequelae.