The binding of five antineutrophil monoclonal antibodies AHN-1, -2, -3, -7, and -8, to normal and leukemic bone marrow cells was studied. AHN-7 bound to many granulocytic precursors, particularly myelocytes, and both lymphoid and blast cells in normal marrow, and to most but not all granulocyte-macrophage progenitors (CFC-GM). AHN-8 bound only to late (band and segmented) neutrophilic cells and not to CFC-GM. AHN-1, -2, - 3 bound to morphologically identifiable neutrophil precursors, but not to (day-14) CFC-GM. Approximately half of nonlymphoid leukemia specimens were positive with AHN-1 or AHN-7; by contrast, lymphoid leukemia specimens were rarely positive. AHN-8 was rarely found on leukemic cells. These antineutrophil antibodies appear to detect distinct granulopoietic subsets and may be useful in the analysis of hematologic differentiation and in the subclassification of leukemias.