Human cyclic neutropenia probably represents a rare group of heterogeneous disorders. The disorder most frequently starts in infancy or childhood. During the neutropenic episodes, the most common symptoms are fever and oral ulceration. However, dental and skin manifestations are frequent and require special attention. While the disease is usually benign and the symptoms may ameliorate as the patient grows older, 15 deaths related to neutropenia have been recorded. While many modalities of treatment have been suggested, none have proved to be universally efficacious. Study of cyclic neutropenia may provide insight into the normal control of granulopoiesis and into the genesis of biological rhythms.