We show here that the maternally inherited Snurf-Snrpn 3-Mb region, which is silenced by a potent transcription repressive mechanism, is uniformly enriched in histone methylation marks usually found in constitutive heterochromatin, such as H4K20me3, H3K9me3, and H3K79me3. Strikingly, we found that trimethylated histone H3 at lysine 36 (H3K36me3), which was previously identified as a hallmark of actively transcribed regions, is deposited onto the silenced, maternally contributed 3-Mb imprinted region