The kinetics of hematological recovery after autologous marrow transplantation have been studied in 70 patients with acute leukemia (38 acute nonlymphoblastic leukemia [ANNL] and 32 acute lymphoblastic leukemia [ALL]). The incidence of graft failure in this group was 3.2%, and a persistent severe thrombocytopenia was observed in 24% of the cases. Variables influencing engraftment have been studied using univariate and multivariate statistical analysis. Analysis of the entire group showed a correlation between graft colony-forming unit granulocyte-macrophage (CFU-GM) content and granulocyte recovery (p < 0.001). Marrow purging was associated with a delayed engraftment (p < 0.001). In ANLL patients, we found that high cummulated AraC doses before marrow cryopreservation correlated with poor granulocyte recovery after marrow infusion (p < 0.002). Platelet recovery was essentially affected by age, with shorter thrombocytopenia periods in younger patients (p < 0.001). Finally, excluding autotransplants with purged marrows, ALL patients showed better platelet recoveries than ANLL patients (p < 0.005). These findings will be useful to evaluate the risk of delayed engraftment after autologous bone marrow transplantation (ABMT) in patients with acute leukemia.