Umbilical cord blood (UCB) has been increasingly used as a source of haematopoietic stem cells (HSCs) for transplantation. UCB transplantation (UCBT) has some advantages such as less stringent human leucocyte antigen (HLA) matching and lower impact of graft-versus-host disease (GvHD). UCBT is also characterised by a high rate of infections, graft failure, delayed engraftment and slow recovery of the immune system. UCB contains HSC as well as immune cells that could be considered to develop new treatments for the main complications post-UCBT but also to treat other diseases. GvHD remains a major complication post-CBT and post-haematopoietic stem cell transplantation (HSCT). In view of their ability to induce tolerance and suppress the functions of effector T cells, regulatory T (Treg) cells have been proposed as an adoptive therapy to modulate GvHD post-HSCT. In addition, we showed that UCB contains soluble NKG2D ligands that can modulate the functions of NKG2D expressing cells, making UCB plasma a product of interest to modulate inflammation and in particular skin GvHD. Here, we aim to describe some of the therapies currently developed using UCB, focusing on Treg cells and UCB plasma for the treatment of GvHD.