BackgroundThe number of aldehyde dehydrogenase–bright (ALDHbr) cells has been suggested as a viable marker of hematopoietic stem cell function. We evaluated the suitability of ALDHbr cell analysis in the quality assessment of postthaw cord blood (CB) units.Study Design and MethodsA total of 245 CB units were obtained for estimating the numbers of total nucleated cells (TNCs), CD34+ cells, ALDHbr cells, ALDHbr cells among CD34+ cells (CD34+ALDHbr cells), CD34+ cells among ALDHbr cells (ALDHbrCD34+ cells), colony‐forming unit (CFU)–granulocyte‐macrophages (GMs), and CFU–granulocyte‐erythrocyte‐macrophage‐megakaryocytes (GEMMs). Simple linear regression analysis was performed to assess the correlation between the number of TNCs and CD34+ cells before and after crypreservation and CD34+ALDHbr cells, ALDHbr cells, and ALDHbr CD34+ cells after cryopreservation and the number of CFU‐GEMMS and CFU‐GMs.ResultsThe number of CFU‐GMs was found to be significantly correlated with the number of CD34+ cells before and after cryopreservation (r = 0.418 and r = 0.359, respectively), CD34+ALDHbr cells, ALDHbr cells, and ALDHbrCD34+ cells (r = 0.426, r = 0.455, and r = 0.469, respectively). The number of CFU‐GEMMs was found to be significantly correlated with the number of TNCs and CD34+ cells before and after cryopreservation (TNCs, r = 0.251 and r = 0.250, respectively; CD34+ cells, r = 0.391 and r = 0.347, respectively), CD34+ALDHbr cells, ALDHbr cells, and ALDHbrCD34+ cells (r = 0.297, r = 0.297, and r = 0.252, respectively).ConclusionThe high correlation found between ALDH activity and CFU‐GM number supports the suitability of ALDH analysis in the quality assessment of postthaw CB units.