Background: Bone marrow graft cell content impacts engraftment potential after allogeneic hematopoietic cell transplantation (alloHCT). Surrogates such as intra-operative total nucleated cell count (ioTNC), are of unclear utility in predicting final graft characteristics. In addition, demographic and clinical factors may influence graft cellular profile and recipient engraftment. Procedure: We retrospectively reviewed marrow harvests at our institution performed between 2009 and 2019. During this time, an ioTNC was measured after 50% of the projected final graft volume was collected. Regression models were used to assess associations between ioTNC (cells/µL) and final graft CD34+ cells/mL, and between graft and donor characteristics and final graft CD34+ cells/mL. Results: Fifty-three marrow harvests and donor-recipient pairs were analyzed. Median (range) donor and recipient ages were 13 (0.7-28) years and 9 (0.2-21) years, respectively. The median ratio of donor/recipient weight was 1.225 (range 0.31-7.13). Median total volume of harvested marrow was 15.3ml/kg (range 4.3-20.4ml/kg) of donor weight and 19.4ml/kg (range 4.7-87.4ml/kg) of recipient weight. Median ioTNC was 20930/µL (range 6600-44310/ µL) or 2.1x109/mL, corresponding to median predicted final graft TNC of 3.59 x108/kg recipient weight (range 1.28-19.42x108). Simple linear regression between ioTNC and CD34+ cells/mL resulted in an R2 of 0.42. LASSO regression produced a moderately predictive model consisting of ioTNC, donor age, and donor weight (adjusted R2=0.7) of final graft CD34+ cells/mL. Conclusions: ioTNC and certain donor characteristic correlate moderately well with marrow product CD34+ cells/m, potentially informing donor selection and marrow procurement strategies.