Aberrant DNA methylation is a common epigenetic alteration and an important feature in human cancers. The DEAD box polypeptide 43 (DDX43) has been found to be overexpressed in various solid tumors and some hematologic malignancies. In the present study, we investigated the methylation status of the DDX43 promoter in 87 Chinese patients with chronic myeloid leukemia (CML) using real-time quantitative methylation-specific polymerase chain reaction and examined the DDX43 transcript in 35 patients using real-time quantitative polymerase chain reaction. DDX43 promoter hypomethylation was observed in 22 (25.3%) CML patients. No significant correlation was found between the hypomethylation of the DDX43 promoter with the age, sex, white blood cell counts, hemoglobin concentration, platelet counts, and chromosomal abnormalities of CML patients (p>0.05). The frequency of DDX43 hypomethylation in patients in the chronic phase, in the accelerated phase, and in blast crisis was 23.4% (15/64), 25.0% (2/8), and 33.3% (5/15), respectively (p>0.05). There was a significant correlation between DDX43 hypomethylation and DDX43 transcript (r=0.469, p=0.004). Our data suggest that hypomethylation of the DDX43 promoter may be an early and frequent molecular event in the development of CML in Chinese patients.