Objective of this study was to investigate the ID4 gene methylation status in patients with acute myeloid leukemia (AML). Methylation-specific PCR (MS-PCR) was used to detect the promoter methylation status of ID4 gene in bone marrow samples from 46 AML patients with different subtypes and stage of disease and from 10 patients with iron deficiency anemia (IDA) as a control. The results showed that ID4 gene in bone marrow of IDA patients was completely non-methylated, while ID4 gene methylation was found in 39 out of 46 AML patients (positive rate 84.8%). The positive rates of ID4 gene methylation in different FAB types M₁, M₂, M₃, M₄, M₅, M₆ were 100% (4/4), 75% (9/12), 100% (8/8), 77.8% (7/9), 81.8% (9/11), 100% (2/2) respectively. The positive rates of ID4 gene methylation in newly diagnosed and complete remitted of AML patients were 90% (27/30) and 63.3% (7/11) respectively; ID4 methylation was detected in 5 relapsed and refractory AML patients. There were statistically significant differences in ID4 gene methylation between AML and IDA patients (p < 0.01). It is concluded that compared with IDA patients, ID4 gene methylation changes of different degrees occur in AML patients with different subtypes and stages, which suggests that ID4 gene methylation may be an early molecular event in the process of AML.