This study was purpose to investigate the difference of Id4 gene promoter methylation between healthy individuals and acute leukemia patients. MS-PCR methods were used to detect the status of Id4 gene methylation in healthy individuals and acute leukemia patients. The results showed that Id4 gene was unmethylated in bone marrow samples from healthy individuals. In new diagnosed AML and ALL patients, the rate of Id4 gene methylation was 84% and 86% respectively. Id4 gene methylation was found in all 8 cases of relapsed acute leukemias. In 14 ALL-CR patients with Id4 gene methylation, 8 patients relapsed within 12 months, while in 9 ALL-CR patients with Id4 gene unmethylation only 1 patient relapsed within 12 months. In AML-CR patients, the 12-months relapse rate in patients with Id4 gene methylation was 62.5%, while it was 10% in Id4 gene unmethylation patients, there was significant difference between them. The rate of Id4 gene methylation in ALL-CR patients was 64.3%, while it was 28.6% in AML-CR patients, there was significant difference between them. In the all 39 new diagnosed AL patients, Id4 gene methylation could be detected in 33 patients. In all 8 relapsed AL patients Id4 gene methylation was found, out of 58 AL-CR cases, 24 patients was found with Id4 gene methylation. It is concluded that as compared with healthy individuals, Id4 gene in acute leukemia patients was methylated in different degrees. The percentage of Id4 gene methylation in AL-CR group is lower than that in AL-non remission group. The change of Id4 gene methylation is thought to be associated with occurrence of acute leukemia.