Objective To investigate the correlation between aberrant methylation status of ras association domain family 1A (RASSF1A) , transcriptional levels of DNA methyltransferases (DNMTs) and hepatitis B virus ( HBV) infection in patients with hepatocellular carcinoma ( HCC). Methods HCC samples in 61 cases were collected. Aberrant methylation status of RASSF1A was detected using methylation specific PCR (MSP). Transcriptional levels of DNMT1, DNMT3 A and DNMT3B was measured using semi-quantitative reverse transcriptase-PCR(RT-PCR). Results RASSF1A gene with abnormal methylation in initiation zone was found in 45 cases with HCC among 61 patients (73.8%). Further analysis revealed RASSF1A methylated in 32 of 47 HBV infected cases and in 13 of 14 uninfected cases. However, there was no significant association between methylation status of RASSF1A and HBV infection (x2 =2.260, P = 0. 133). Compared with normal control, DNMTs was up-regulated in all HCC samples, HCC cell lines and HBV infected group. Analysis within each group indicated that DNMT3A and DNMT3B levels of HCC increased in MSP positive cases ( t = 3. 494, P