To describe the incidence, epidemiology, clinical presentation and clinical outcome of children with the syndrome of periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) in a population-based study. In a prospective population-based study, all children in South Rogaland, Norway, diagnosed with PFAPA during 2004-2010 were evaluated clinically, and parents were interviewed systematically. A follow-up interview was performed for all patients. A total of 46 children (32 boys; p = 0.011) were diagnosed with PFAPA. We calculated an incidence of 2.3 per 10 000 children up to 5 years of age. The median age of onset was 11.0 months (quartiles: 5.0, 14.8). Nearly 37 children were followed until resolution. In 17 of these, a tonsillectomy was performed with prompt resolution of PFAPA in all. The median age of spontaneous resolution was 60.2 months (range 24-120) and in children with tonsillectomy 50.9 months (range 15-128). The incidence of PFAPA was 2.3 per 10 000 children up to 5 years of age. In the majority of cases, onset of symptoms may be during the first year of life. ©2012 The Author(s)/Acta Paediatrica ©2012 Foundation Acta Paediatrica.