Recently, several groups described the isolation of mouse spermatogonial stem cells (SSCs) and their potential to develop to embryonic stem cell (ESC)-like cells, so-called multipotent germline stem cells (mGSCs). We were the first to derive such mGSCs from SSCs isolated from adult mouse testis and, therefore, called these mGSCs multipotent adult germline stem cells (maGSCs). Here, we comparatively analyzed gene-specific and global DNA methylation profiles as well as the telomerase biology of several maGSC and male ESC lines. We show that undifferentiated maGSCs are very similar to undifferentiated male ESCs with regard to global DNA methylation, methylation of pluripotency marker gene loci, telomerase activity and telomere length. Imprinted gene methylation levels were generally lower in undifferentiated maGSCs than in undifferentiated male ESCs, but, compared with undifferentiated mGSCs derived by other groups, more similar to those of male ESCs. Differentiation of maGSCs increased the methylation of three of the four analyzed imprinted genes to almost somatic methylation patterns, but dramatically decreased global DNA methylation. Our findings further substantiate the pluripotency of maGSCs and their potential for regenerative medicine.