Methylated DNA immunoprecipitation (MeDIP) is a versatile immunocapturing approach for unbiased detection of methylated DNA. In brief, genomic DNA is randomly sheared by sonication and immunoprecipitated with a monoclonal antibody that specifically recognizes 5-methylcytidine. The resulting enrichment of methylated DNA in the immunoprecipitated fraction can be determined by PCR to assess the methylation state of individual regions. Alternatively, MeDIP can be combined with large-scale analysis using microarrays as a genome-wide experimental readout. This protocol has been applied to generate comprehensive DNA methylation profiles on a genome-wide scale in mammals and plants, and further to identify abnormally methylated genes in cancer cells.