Objective To study the significance of kinetic detection of the PML RARα fusion gene in the treatment of childhood acute promyelocytic leukemia (APL). Methods Ten children with APL were involved in this study. They were administered with all trans retinoic acid (ATRA) alone or with ATRA plus other chemotherapeutic drugs during remission induction, consolidation and maintenance treatments and were followed up. The bone marrow samples were regulary collected for morphological evaluation and PML RARα fusion gene detection (by RT PCR assay). Results The median follow up time was 42 months (ranging from 14 to 156 months). The estimated 5 year disease free survival rate was 56.0 ± 18.5% . Clinical complete remission (CR) was obtained in 9 cases (90%) and 1 case died on the 4th day after ATRA treatment. Of the 9 cases, 4 cases relapsed 14-42 months after CR and 5 cases remained continuous CR. Among the 4 cases with relapse, the PML RARα fusion gene was positive in 2 cases and it converted into positive in another 2 cases. Of the 5 cases with continuous CR, 3 cases with a positive PML RARα fusion gene 24, 42 and 36 months after CR were given salvage therapy. After the salvage treatment, the 3 cases had negative PML RARα fusion gene. Conclusions A continuous negative PML RARα fusion gene may be associated with long term disease free survival. The kinetic detection of PML RARα is important for modifying treatment and for preventing hematological relapse in the treatment of APL.