Objective: To investigate the clinical treatment results of combined Tretinoin-chemotherapy protocol and kinetics of PML-RAR ? fusion gene in childhood acute promyelocytic leukemia(APL). Methods: Ten children with APL were involved in this study. Induction therapy was Tretinoin alone(6 cases),Tretinoin plus chemotherapy(3 cases) and arsenic trixode(1 case). Postremission therapy consisted of three consolidation courses with DA,MA or HA and a monthly maintenance therapy over 4-5 years. Monitoring of minimal residual disease was performed regularly by RT-PCR assay for PML-RAR ? at differential clinical stages. Results: Clinical complete remission(CR) was obtained in 9 cases (90%).After a median follow-up of 42 months(14-156 months), the estimated 5-year event-free survival was (56? 16.5)%.Four cases relapsed at 14-42 months after achieving CR and 5 cases remained continuing CR. PML-RAR ? fusion gene was positive in all cases at CR and turned negative gradually during consolidation and maintenance treatment. The duration of conversion to RT-PCR negative status varied from 6 to 42 months.Four patients who were persistent positive(2 cases) or converted to positive(2 cases) for PML-RAR ? relapsed. Conclusion: Continuous negative RT-PCR results are associated with long-term disease-free survival and may be considered as potentially curative. RT-PCR assay for detection of PML-RAR ?should be performed regularly during post-remission period. The hematological relapse could potentially be averted through treatment modification according to molecular monitoring results of PML-RAR ?.