The objective of the study was to evaluate the current standard practice of using volume and total nucleated cell (TNC) count for the selection of cord blood (CB) units for cryopreservation and further transplantation. Data on 794 CB units whose CD34+ cell content was determined by flow cytometry were analyzed by using a receiver operating characteristic (ROC) curve model to validate the performance of volume and TNC count for the selection of CB units with grafting purposes. The TNC count was the best parameter to identify CB units having 2 × 10(6) or more CD34+ cells, with an area under the ROC curve of 0.828 (95% confidence interval, 0.800-0.856; P < .01) and an efficiency of 75.4%. Combination of parameters (TNC/mononuclear cells [MNCs], efficiency 74.7%; TNC/volume, efficiency 68.9%; and volume/MNCs, efficiency 68.3%) did not lead to improvement in CB selection. All CB units having a TNC count of 8 × 10(8) or more had the required CD34+ cell dose for patients weighing 10 kg or less.