Aim: The aim of this study was to identify factors that may be related to the development of engraftment following peripheral stem cell infusion after myeloablation. Material and Method: The data of 121 patients who underwent autologous hematopoietic stem cell transplantation were retrospectively reviewed. Of the patients, 39 (32%) had multiple myeloma (MM), 34 (28%) had non-Hodgkin lymphoma (NHL), 33 (27%) had Hodgkin lymphoma (HL), 9 (8%) had acute leukemia and 6 (5%) had solid tumor. BEAM (carmustine, etoposide, arabinoside-C, melphalan), high doses of ICE (ifosfamide, carboplatin, etoposide), ME (melphalan plus etoposide), BuCy (busulfan and cyclophosphamide), and melphalan were used as preparation regimes. The mean age was 41.3 years with a median of 43 years (range 16-71 years). To identify factors that may be relevant in the development of engraftment following stem cell infusion, preparation regime, type of growth factor, total CD34+ cell count, and neutropenic fever occurrence were evaluated. Results: Neutrophil > 500/mu l and plt > 20,000/mu l levels were achieved at 10,1 +/- 2,3 and 11,5 +/- 3,9 days, respectively. Patients age, gender, diagnosis, radiotherapy before transplantation, and G-CSF administration had no significant effect on engraftment time. It was found that platelet engraftment was more rapid in patients who underwent ICE than in those who underwent the BEAM preparation regime; in addition, it was found that neutrophil engraftment was more rapid in patients who underwent ICE than in those who underwent the melphalan preparation regime. No direct correlation was demonstrated between CD34+ cell count and engraftment, while the engraftment was found to be more rapid in higher CD34+ cell counts. Discussion: Further studies are needed to identify the optimal peripheral stem cell transplantation protocol to improve bone marrow regeneration; to accelerate hematopoietic regeneration after myeloablative therapy; and to determine factors influencing engraftment.