A 59-year-old female of adult-onset cyclic neutropenia with 15 day cycle is reported. The peripheral blood picture revealed that the neutropenia recurred every 15 days. The other formed elements of the blood such as monocytes, platelets and reticulocytes also showed periodic fluctuations corresponding to cyclic hematopoiesis. As with the cycle in peripheral blood, myeloid series in the marrow also cycled successively from myeloblasts to segment forms. The concentration of CFU-C decreased prior to the neutropenic episode. The surface marker analysis of the lymphocytes revealed the increase in OKT8 population at the neutropenic phase and the chemiluminescence of neutrophils and monocytes were accerelated at febrile state.
