Mouse genomes show a large cluster of imprinted genes at the Dlk1-Gtl2 domain in the distal region of chromosome 12. An intergenic-differentially methylated region (IGDMR) located between Dlk1 and Gtl2 is specifically methylated in the male germline; IG-DMR regulates the parental allele-specific expression of imprinted genes. Here, we show the resetting of IG-DMR methylation marks during male germ-cell differentiation. For parental allele-specific methylation analysis, polymorphisms were detected in a 2.6-kb IG-DMR in three mouse strains. Bisulfite methylation analysis showed erasure of the marks by E14 and re-establishment before birth. The IG-DMR methylation status was maintained in spermatogonia and spermatocytes of mature testes. The IG-DMR methylation status established before birth is thus maintained throughout the lifetime in the male germline. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.