Circulating　DNA　is　a　potential　biomarker　for　tumor　diagnosis　and　prognosis.　This　study　was　aimed　to　quantify　the　circulating　DNA　in　plasma　from　patients　with　hepatocellular　carcinoma　(HCC)　using　quantitative　PCR　and　evaluate　its　potential　clinical　value.　Blood　samples　were　collected　from　72　patients　with　HCC,　37　with　liver　cirrhosis　or　chronic　hepatitis　and　41　healthy　volunteers.　Plasma　DNA　was　extracted　and　quantified　by　a　real-time　quantitative　PCR　method.　The　diagnostic　and　prognostic　value　of　plasma　DNA　analysis　for　HCC　was　evaluated.　DNA　levels　in　the　HCC　plasma　(median:　173　ng/mL)　were　significantly　higher　than　those　in　the　healthy　controls　(9　ng/mL)　or　control　benign　patients　(46　ng/mL)　(P＜0.001).　The　area　under　the　receiver-operation　characteristic　(ROC)　curve　(AUC)　assessing　plasma　DNA　was　0.949　for　healthy　controls　and　0.874　for　control　patients.　Plasma　DNA　detection　could　discriminate　HCC　from　normal　controls　with　90.2%　sensitivity　and　90.3%　specificity　at　the　cut-off　value　of　18.2　ng/mL.　Combined　ROC　analyses　using　plasma　DNA　and　serum　AFP　revealed　an　elevated　AUC　of　0.974　with　95.1%　sensitivity　and　94.4%　specificity　in　discriminating　HCC　from　normal　controls.　The　plasma　DNA　levels　were　positively　associated　with　tumor　size　(P=0.012),　and　were　significantly　elevated　in　HCC　patients　with　intrahepatic　spreading　or　vascular　invasion　(P=0.035).　The　overall　survival　time　of　patients　with　high　plasma　DNA　levels　showed　a　shortened　tread　when　compared　with　that　of　patients　with　low　plasma　DNA　concentrations　(P=0.071).　Plasma　DNA　may　be　a　valuable　noninvasive　tool　for　the　detecting　and　predicting　the　metastasis　potential　of　HCC;　and　the　prognostic　value　of　plasma　DNA　needed　further　investigation.