Tumor necrosis factor receptor-1-associated periodic syndrome (TRAPS) is the most common autosomal dominant autoinflammatory disorder and is caused by mutations in the TNFRSF1A gene encoding the 55-kDa receptor for tumor necrosis factor (TNF)-α. TRAPS is characterized by recurrent attacks of fever, typically lasting from 1 to 3 weeks. In addition to fever, common clinical features include periorbital edema, a migratory erythematous plaque simulating erysipela with underlying myalgia, and arthralgia or arthritis. Serosal membrane inflammation is also a common feature, usually in the form of polyserositis. To date, at least 40 different TNFRSF1A mutations have been identified, but few patients with symptoms highly suggestive of TRAPS with no mutations in the TNFRSF1A gene have recently been described, thus suggesting that not all mutations are yet known or that alternative mechanisms might be involved in the pathogenesis of the disease. We report on three such patients here.