The study was aimed to investigate the relation between the expression level of TEL-AML1 (translocation ETS leukemia-acute myeloid leukemia 1) fusion gene and clinical characteristics as well as early response to treatment in children with ALL (acute lymphoblastic leukemia). With real-time quantitative polymerase chain reaction (RQ-PCR), the expression level of TEL-AML1 at diagnosis and MRD (minimal residual disease) at the end of induction of remission were detected in 35 children with ALL, including 20 SR (standard risk) and 15 IR (intermediate risk) patients. The expression level of TEL-AML1 and clinical characteristics at diagnosis were compared between MRD negative and MRD positive patients. The relation between TEL-AML1 expression levels at diagnosis, MRD level and clinical characteristics as well as early response to treatment were also explored. The results indicated that the expression levels of TEL-AML1 at diagnosis were 1.63 x 10(4) copies/10(4) copies ABL (median). At the end of induction of remission, 16 patients (10 SR and 6 IR patients) did not achieve molecular remission, whose MRD levels were 0.84 - 282.93 copies/10(4) copies ABL. No relation was found between expression levels of TEL-AML1 at diagnosis and clinical characteristics as well as MRD level. There was a significant relation between MRD level and blast count in peripheral blood (PB) at day 8 after prednisone trial induction. Significant relations between MRD level and presenting leukocyte count, blast percentage in PB were also found in the patients with presenting leukocyte count < 25 x 10(9)/L. TEL-AML1 expression level at diagnosis of MRD negative patients was lower than that of MRD positive ones. It is concluded that therapy after induction of remission is of importance by the fact that 45.71% children with TEL-AML1(+) ALL did not achieve molecular remission at the end of induction of remission. The effectiveness of prednisone trial predicts the MRD level. In addition, presenting leukocyte count, blast percentage in PB and TEL-AML1 expression level at diagnosis may have an effect on MRD level to some extent.