Epigenome editing is a promising approach with many therapeutic applications. It is based on synthetic epigenetic enzymes, so called EpiEffectors, which are fused to desigened DNA binding proteins bringing them to defined genomic target sites. Epigenome editing in the past was hampered by the difficulties in designing the necessary DNA binders. Recently, the CRISPR-Cas system was discovered, allowing to bind any DNA sequence. Its specificity is determined by a guide RNA component of the CRISPR-Cas complex, that can be easily altered. Here we have used CRISPR-Cas to target DNA methylation in cells using an optimized DNMT3A enzyme. We show that efficient methylation depends on the ability of DNMT3A to from fibers on the target DNA.