['To investigate the possibility of identifying DNA hypermethylation in the circulation of prostate cancer patients.', 'Plasma DNA samples were extracted from 36 prostate cancer patients and 27 benign prostate hyperplasia (BPH) cases. After extensive methylation-sensitive restriction enzyme digestion, the DNA samples were subjected to the real-time quantitative PCR amplification. Dissociation curve analysis was applied to determine if hypermethylation occurred in the promoter region flanking the GSTP1 gene, a well-documented epigenetic event among prostate cancer cells, in these plasma DNA samples.', '11 of 36 prostate cancer patients showed positive peak pattern, indicating methylation changes occurred. Concordant data were obtained from the corresponding paraffin-embedded tissue samples available from the Tumor Bank. Twenty-five of the 27 BPH cases showed negative results, suggesting no methylation changes happened in the CpG islands in these cases.'] Is hypermethylation of the CpG islands in the promoter region flanking GSTP1 gene a potential plasma DNA biomarker for detecting prostate carcinoma?