I've just done strip tests on two rolls of expired HIE. One 04/2006 and other 08/2008. IIRC both were refrigerated till a few months after expiry date and then frozen (approx -20C) The conclusion is simple - I cannot tell the negs by looking side by side, base is clear. I probably won't have time to make contact proofs till at least next week so I can't really say if everything is ok but the fact that both look the same (and that 06 was ok last summer) strongly suggests that it indeed is. Or am I saying something that is well known? I've searched for a while but found some vague statements about expired hie being ok.