The present invention relates to a method for the quantification of methylated cytosines in DNA. In the first step of the invention unmethylated cytosines in the DNA to be analysed are chemically converted into uracil while 5-methylcytosines remain unchanged. In a second step the converted DNA is amplified methylation specifically in a real time PCR using a methylation specific probe. Finally the amount of uniformly methylated DNA is calculated by combining criteria derived from the shape of the real time curve and from the signal intensity. The method is preferably used for diagnosis and/or prognosis of adverse events for individuals, for distinguishing cell types and tissues, or for investigating cell differentiation.