Methylation-specific polymerase chain reaction (MSP) is a method that can rapidly assess the methylation status of virtually any group of CpG sites within a CpG island, independent of the use of methylation-sensitive restriction enzymes. This assay entails the initial modification of DNA by sodium bisulfite, converting all unmethylated cytosines to uracils but leaving the methylated cytosines unchanged, followed by subsequent amplification with primers specific for methylated vs unmethylated DNA. The great sensitivity of this technique allows qualitative methylation analysis from DNA obtained not only from fresh frozen tissues, peripheral blood, bone marrow, or body fluids but also from paraffin-embedded samples. It is a rapid and cost-effective method that does not require radioactive reagents and can be used for the analysis of a large number of clinical samples.