Abstract: A genome wide microarray gene expression approach for human colorectal cancer cells was used to identify hundreds of hypermethylated genes for colon cancer. We compared isogenic cells altered pharmacologically versus genetically to induce genomic demethylation, to pinpoint genes activated by DNA demethylation, but not by inhibition of class I and II histone deacetylases (HDACs). We achieve an 82% success rate in predicting genes with densely hypermethylated CpG islands and complete gene silencing. The genes are similarly hypermethylated in primary tumors and have previously undetected tumor suppressor functions. The genes can be used diagnostically to detect cancer, pre-cancer, and likelihood of developing cancer.