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Background: The improved prognosis for early-detected colorectal cancer (CRC) has supported the value of CRC screening.However, compliance is very low, partly due to the inconvenience and unpleasant nature of colonoscopy and fecal sampling.The availability of a blood-based test for CRC detection might improve compliance and enable early detection of more cancers.Detection of methylated Septin 9 DNA in plasma has been associated with CRC in prior studies.We report herein the development and validation of a clinical test (ColoVantageTM) for methylated Septin 9 DNA in plasma.Methods: Total nucleic acids were extracted from plasma using the Chemagen MSM platform.Bisulfite conversion and purification of DNA was performed using the Zymo Research DNA Direct kit.Methylated Septin 9 DNA was detected using methylation-specific real-time PCR.We evaluated sensitivity, specificity, and clinical performance using plasma samples from colonoscopy-negative individuals and CRC patients at varying stages.Results: The PCR was specific for methylated DNA in the range of 0.0005-50rig DNA/reaction.No Septin 9 PCR products were detected at the same concentrations of unmethylated DNA.Five of 46 (11%) colonoscopy-negative individuals tested positive for methylated Septin 9 DNA.The detection rate among CRC patients was 12/18 (67%) stage Ⅰ, 8/18 (44%) stage Ⅱ, 7/10 (70%) stage Ⅲ, and 5/5 (100%) stage Ⅳ cases.The overall clinical sensitivity was 63%, and the specificity was 89%.Conclusions: This methylated Septin 9 DNA PCR test (ColoVantage TM) is highly sensitive and specific for detection of the analyte.In patient samples, the assay has a clinical sensitivity and specificity comparable to fecal occult blood (FOBT) and immunochemical tests.Thus, the ColoVantageTM assay may prove to be useful for identifying patients at risk of colorectal cancer.