Abstract:  Cryopyrin-associated periodic syndromes (CAPS) are characterized by apparently unprovoked attacks of fever, rashes, and musculoskeletal and sensorineural inflammation accompanied by high acute-phase reactants. Excessive interleukin-1 (IL-1) signaling appears to be a constant feature in the pathomechanism of the disease, driven by a gain-of-function mutation in the NLRP3 gene. Herein, we present the case of a 9-month-old boy with recurrent nonpruritic rashes and episodes of fever. The difficulties of early diagnosis due to initially mild clinical symptoms and the dramatic response to anti-IL-1 therapy after diagnosis emphasize the practical relevance of considering CAPS as a differential diagnosis in these patients.