Backgrounds: High-dose chemotherapy and subsequent hematopoietic rescue with autologous perip heral blood stem cells (PBSC) has widely used with stage Ⅳ neuroblastoma in ord er to improve survival and possible and the possibility of recurrence due to rei nfusion of the tumor cell has known. Currently, selective separation method of C D34 positive stem cells and reinfusion is tried. We observed the result of selec tive separation of CD34 positive stem cells using avidin/biotin immunoabsorption column method and the result of reinfusion using the product. Methods: Nine stage Ⅳ neuroblastoma patients were enrolled in the study. PBSC was mobili zed with chemotherapy and G-CSF. CD34-positive selection was performed using avi din/biotin immunoabsorption column (CEPRATE, CellPro, Bothell, WA, USA) method. Compare between Cd34-positive stem cell count before and after separation was do ne. After collection of C34-positive stem cells enough to reinfusion, high-dose chemotherapy followed by PBSC transplatation was done. Results: A total of 14 leukaphereses were performed in 9 patients. The mean number of col lected CD34-positive stem cells before and after CD34-positive selection was 4.3 ×106/㎏(0.47-14.1×106/㎏) and 1.7×106/㎏ (0. 08-6.7×106/㎏), respectively. The mean yield and the mean purity of CD34-positive stem cells were 35.1±18.6% and 23.9±13.8%, respectively. Seven p atients received CD34-positive selected PBSC product. Median engraftment period of WBC and platelet was 11 days and 55 days, respectively. Median follow up peri od was 10 months(2∼22 months). Three patients receiving PBSC were recurred. Two of recurred patients were died after PBSC transplantation on 5 months and 14 mo nths, respectively. Five patients are alive with no evidence of disease. Conclusion: Reinfusion of CD34-positive selected products from PBSC with high-dose chemother apy were engrafted successfully in all stage Ⅳ neuroblastoma patients. But, thr ee of the patients revealed recurrence of the disease. However, more selective s eparation method of CD34-positive stem cells from harvested products should be e valuated further.