The value of the Giemsa stain on smears and imprints has long been acknowledged, but few pathologists have been consistently successful with histologic sections because of the peculiar problems of the dyes and the mysterious vagaries of the methodology. A Giemsa stain giving reproducible differential staining of tissue sections is particularly desirable for the examination of hematopoietic tissues. A modified Giemsa stain which provides such reproducibility is described. It differs from other methods primarily in the use of a stock solution which contains known amounts of azure A–eosin and azure B–eosin. In addition, acetic acid is used instead of phosphate buffers to obtain an acidic working solution. The results suggest that the Giemsa stain may represent the most useful means of evaluating lymphoid tissue in section. It is of particular value in identifying the immunoblast (basophilic stem cell), as well as providing differentiation of granulocytic elements.