Development of high-throughput sequencing technologies now enables genome-wide analysis of DNA methylation of mammalian cells and tissues. Here, we present a protocol for Reduced Representation Bisulfite Sequencing (RRBS) applicable to low amounts of starting material (from 200 to 5,000 cells). RRBS is a cost-effective and powerful technique offering the advantages of absolute DNA methylation quantification and single nucleotide resolution while covering mainly CpG islands. Typically one sequencing experiment using the Illumina Genome Analyser IIx platform provides information on the DNA methylation status of more than half of the CpG islands of the mouse genome.