ABSTRACTChronic neutropenia is a term used to describe a group of disorders characterized by a persistent neutrophil count of less than 1500 cells/μl. We studied seven children and three sets of parents. We separated patients into a group with good prognosis and a group at higher risk of infection by using a combination of tests, including bone marrow aspiration and biopsy, steroid stimulation of bone marrow reserve, andin vitroCFU-GM and CSA assays. Children with a normal number of myeloid elements in their bone marrow and a normal bone marrow response to steroid stimulation had a benign course. CFU-GM and CSA assays helped to classify these children's neutropenia when their bone marrow had decreased numbers of myeloid elements. Family studies in three children were consistent with an inherited neutropenia, even when their parents were hematologically normal.