Introduction: The PFAPA (Periodic Fever, Adenitis, Pharyngitis, Aphtous Stomatitis) syndrome is characterized by periodic fever, aphthous stomatitis, pharyngitis, and adenopathy. It is a benign sporadic condition, the cause and physiopathology of which is still unknown. It affects children younger than 5 years, with an average age of 2.8 years, and slight predominance in men. The diagnostic criteria are clinical, with no specific complementary examinations existing. A response to corticoid corroborates the diagnosis, suggesting mediation of cytokines as mechanism and not an infectious process.