Mevalonate kinase deficiency is a rare inborn disorder of isoprenoid and sterol biosynthesis characterized by a recurrent autoinflammatory syndrome and, in most severe cases, psychomotor delay. Clinical manifestations can be very complex and, in some cases, mimic a chronic inflammatory disease. Diagnosis is also complex and often requires immunologic, genetic, and biochemical investigations. There is no standardized therapy, but biological agents could help to control inflammatory complaints in some cases. A severe case of mevalonate kinase deficiency that was associated with nephritis and successfully treated with anakinra (interleukin 1 receptor antagonist) is reported here, and new insights into diagnosis and therapy of this complex disorder are discussed.