Intermittent hydrarthrosis (IH) is a rare condition characterised by its periodic schedule: recurrent self-remitting episodes of acute arthritis with a fixed periodicity; this clinical picture has been recognised as a clue for diagnosis for a long time.1 The pathogenesis of IH is unknown. An involvement of mastocytes has been reported.2 Interestingly, Cañete et al 3 found mutations of the Mediterranean fever gene (MEFV) in a small series of patients with IH. For management of the disease, non-steroidal anti-inflammatory drugs, corticosteroids and colchicine are used, generally with good results, but some patients persist with recurrent episodes of arthritis. Here we report our experience with the interleukin-1 (IL-1) inhibitor anakinra in a patient with a …