We have previously shown that allogeneic bone marrow transplantation (BMT) with cryopreserved donor marrow cells can be used without prolonging the engraftment time or interfering with the reconstitution of haemopoiesis. In this report we extend our initial observations of the first 40 patients who underwent allogeneic bone marrow transplantation from related donors with cryopreserved donor bone marrow for haematological malignancies, including the long-term follow-up data of the previously reported patients. The outcome of these patients was compared with that of 40 related BMT recipients receiving fresh donor bone marrow (historic control group). Time until engraftment of all patients receiving cryopreserved bone marrow was not different from the control group (ANC > 0.5 x 10(9)/l 17d (range 11-24 d) versus 17.5 d (range 10-28 d): platelets > 20 x 10(9)/l 21 d (range 11-85 d) versus 22 d (range 13-69 d), respectively). There was the same incidence of acute and chronic GvHD in patients receiving either cryopreserved bone marrow or fresh bone marrow (acute GvHD > or = II 61% v 60% and chronic GvHD 56% v 52%, respectively). Chimaerism studies showed no difference between the patient groups. Furthermore, the two groups did not differ in day 100 survival (82% v 72%). With a median follow-up of 520 d (range 47-1365 d) and 1289 d (range 48-1849 d), 60% of the patients receiving cryopreserved and 53% of the patients receiving fresh allogeneic donor bone marrow, respectively, are alive. We conclude that cryopreservation of allogeneic related donor bone marrow does not adversely affect engraftment, does not decrease the incidence of severe acute GvHD, and does not seem to affect the day 100 survival or long-term haemopoiesis.