The cryopyrin-associated periodic syndrome is a very rare disease. It is estimated that there are 1-2 cases out of 1 million inhabitants in the USA and 1/360,000 in France. However, many patients are diagnosed very late or not at all. Therefore the real prevalence is likely to be higher. CAPS encompasses the three entities familial cold autoinflammatory syndrome (FCAS), the Muckle-Wells syndrome and the neonatal-onset multisystem inflammatory disease (NOMID)/chronic infantile neurologic cutaneous and articular (CINCA) syndrome. They have in common a causative mutation in the NLRP3-gene. The altered gene product cryopyrin leads to activation of the inflammasome which in turn is responsible for excessive production of IL-1β. IL-1β causes the inflammatory manifestations in CAPS. These appear as systemic inflammation including fever, headache or fatigue, rash, eye disease, progressive sensorineural hearing loss, musculoskeletal manifestations and CNS symptoms (NOMID/CINCA only). With the advent of the IL-1 inhibitors anakinra, rilonacept and canakinumab for the first time safe and effective therapeutic options are available for this devastating disease. To prevent severe and possible life-threatening disease sequelae, early and correct diagnosis and immediate initiation of therapy are mandatory.