Anticytokine autoantibodies are an important and emerging mechanism of disease pathogenesis. We will review the clinical and laboratory features of syndromes in which immunodeficiency is caused by or associated with neutralizing anticytokine autoantibodies. A growing number of patients have been described who demonstrate unique infectious phenotypes associated with neutralizing autoantibodies that target a particular cytokine known to participate in host defense against the offending organism. Examples include antigranulocyte macrophage-colony stimulating factor (GM-CSF) autoantibodies and pulmonary alveolar proteinosis; anti-interferon (IFN)-γ autoantibodies and disseminated nontuberculous mycobacteria (NTM); anti-interleukin-(IL)-6 autoantibodies and severe staphylococcal skin infection; anti-IL-17A, anti-IL-17F, or anti-IL-22 autoantibodies in patients with mucocutaneous candidiasis in the setting of both the autoimmune polyendocrinopathy, candidiasis, ectodermal dystrophy (APECED) syndrome and in cases of thymoma. Anticytokine autoantibodies have manifestations that are diverse, ranging from asymptomatic to life-threatening. These emerging and fascinating causes of acquired immunodeficiency may explain some previously idiopathic syndromes.