The understanding of normal surface maturation pattern of granulocytes plays an essential role in identifying abnormal patterns, which may be of diagnostic or pathogenetic significance in some disorders, such as myclodysplastic syndromes. CD24, which is expressed only on granulocytes and not on monocytes, has not been adequately studied. Surface marker studies on eight control marrows indicate that CD24 is expressed on bone marrow granulocytes in a pattern that is similar to CD11b while much different than the more mature markers, CD16b and CD35. Three sorting experiments show that the majority of CD24− cells are promyelocytes. We conclude that CD24 is expressed on the neutrophilic granulocytes at the stage of myelocytes, and hence it could potentially be used to study normal and abnormal maturation of granulocytes. Am. J. Hematol. 71:348–349, 2002. © 2002 Wiley-Liss, Inc.