The study was aimed to explore the relationship between patterns of methylation or deletion and the development of acute leukemia, and further to clarify the possible mechanism in the development of adult acute leukemia. Nested methylation-specific polymerase chain reaction (n-MSP) was adopted to analyze p16 gene methylation or deletion patterns in 82 adult acute leukemia patients with different subtypes and stages. The results indicated that rate of p16 gene methylation was 39.0% in 82 adult acute leukemia patients, among them, 41.4% in acute myelogenous leukemia (AML) and 33.3% in acute lymphoblastic leukemia (ALL). It were found that 36.6% of de novo AL patients and 54.5% of relapsed AL patients developed the hypermethylation of p16 gene. Out of the 82 patients, 6 seemed to have deletion of p16 gene, including 1 AML (1.7%) and 5 ALL (20.8%). There were no hypermethylation or deletion of p16 gene in the 16 controls. It is concluded that methylation of p16 gene may play a more important role than homozygous deletion of p16 gene in the leukemogenesis and progression of adult acute leukemia.