Use of cryopreserved donor bone marrow may facilitate scheduling of allogeneic bone marrow transplantation (BMT) by affording independence of a fixed time for bone marrow donation. The potential risk of damage to hematopoietic stem cells by cryopreservation resulting in delayed engraftment or graft failure has to be taken into account, however. To address these issues, the outcome of 19 matched related BMT (1992-94) performed with cryopreserved donor bone marrow was analyzed and compared with 19 related BMT (1990-93) receiving fresh donor bone marrow (control group). Time to engraftment of patients receiving cryopreserved bone marrow was not different from the control group (ANC > 0.2 x 10(9)/l 15.5 +/- 3.8 days vs 15.8 +/- 5.0 days; ANC > 0.5 x 10(9)/l 17.3 +/- 4.1 days vs 17.9 +/- 5.0 days, respectively). We did not find the previously described trend toward a lower incidence of acute GVHD in patients receiving cryopreserved bone marrow compared with patients receiving fresh bone marrow (acute GVHD > or = II 78 vs 64%). Furthermore, the two groups did not differ in the incidence of chronic GVHD (55 vs 38%) or day 100 survival (74 vs 68%). We conclude that in allogeneic BMT cryopreserved bone marrow cells can be safely used without jeopardising or prolonging time to engraftment.