Although miRNAs have been profiled for selected hematopoietic lineages, absolute quantification of miRNA Tasocitinib levels across multiple blood cell types has not been performed. The goals of our study were to quantify the miRNA contents of normal human platelets, T-lymphocytes, B-lymphocytes, granulocytes and erythrocytes on a per cell and per blood volume basis, to determine whether the expression of individual miRNAs differed by cell type, and to explore the potential for exploiting endogenous miRNA levels to modify exogenous gene expression in a hematopoietic cell-specific manner. We found that nucleated cells had substantially higher miRNA content on a per cell basis, but that the hematopoietic cellular contribution to miRNA content of blood on a volume basis was highest in erythrocytes, platelets, T-cells and B-cells. Identification of miRNAs that were differentially expressed across hematopoietic cell lines enabled cell-specific regulation of transgene expression. Circulating blood miRNAs systemically regulate gene expression and are emerging as important disease biomarkers. We report an unbiased, genome-wide profiling and cross-lineage comparisons of 623 miRNAs from highly purified normal primary human blood platelets, T-cells, B-cells. We also provide more precise estimates of blood cell RNAs than have been previously reported, and identify appropriate miRNAs for normalization when comparing miRNA measures across hematopoietic cell types. These findings provide a potential refinement for hematopoietic lineage classification, a framework for designing and interpreting miRNA-disease association studies and opportunities to design gene expression vectors that minimize off-target effects. Estimates of blood cell total RNA content is of interest for optimal design and interpretation of gene expression and biomarker studies. In addition, assessing lineage-specific gene expression requires isolating RNA from highly purified cells. Most prior estimates of blood cell total RNA or miRNA content used density centrifugation for cell purification or could not make quantitative estimates. Unfortunately, density centrifugation alone results in substantial leukocyte contamination of platelet and erythrocyte preparations, compromising estimates of the RNA content of non-nucleated cells because of the higher RNA content of nucleated cells. We used density centrifugation followed by immunoselection with cell-specific markers to isolate highly purified populations, an approach considered state-of-the-art for RNA expression analyses. The purification procedure used in the current report yields less than 1 leukocyte per 5 million platelets. In addition, by using the numbers of cells from which RNA was extracted, we were able to make quantitative estimates of RNA per cell. We found the total RNA mass per leukocyte and per erythrocyte were similar to other reports. We estimated a total RNA content of 2.20 femtograms per platelet. Prior estimates of platelet RNA content were based on an uncertain number of platelets derived from density centrifugation of buffy coats.