We have previously successfully expanded functional T-cells in vitro from cord blood grafts used for clinical transplantation, with the aim of creating donor lymphocyte infusions to treat e.g. malignant relapse. Here we show that the T-cell expansion in addition might work as a prognostic tool for complications after transplantation. We used multi-color flow cytometry to correlate in vitro phenotypical and functional data from 33 expansions to clinical outcome post-transplantation. Higher levels of CD69+ activated T-cells in the expansion were associated with prolonged survival of the patient. In addition, we found a correlation between T-cell expansions containing relatively high levels of effector memory T-cells and graft vs. host disease and relapse. Our data suggest that expansions of cord blood T-cells from the graft might not only be used as donor lymphocyte infusions, but also as in vitro indicators that could give essential information on how to manage cord blood transplanted patients.