Thirty two patients with hematologic malignancies and solid tumors were treated with intensive therapy and autologous bone marrow transplantation. In nine out of 32 patients, it took more than 50 days to achieve a sustained platelet count of 50,000/microliter or greater. Significant associations with poor platelet recovery were found for patient age, diseases, period of cryopreservation, the kinds of eradicative therapy and in vitro purging. But most of these factors overlapped each other in the same patients. No correlation was found between platelet recovery and number of cells or CFU-GM infused.