User blog comment:NecrusIV/Average age of a Space Marine/@comment-3258762-20120815114925

Well, Dante is over 1000 years old, and many Marines serve for over 200 years.

But, as of the 41st millenia, atleast in the Space Wolves codex, the Wolf Lords (who are the greatest of the Space Wolves warriors) seem to have a life expectansy of around 5-30 years (is true, in the codex they have 4 different stories which all involves different Wolf Lords who seem to have been replaced about 6 years later :3)

But i would guess about 200 would be expected.