Are you sure you're blood wasn't just low?

Yes,my status was al nice: ENEGIZED, HYDRATED, Stuffed, Healthy.

I can also report this, a zombie gave my perfectly healthy friend a hay maker that he didn't live long enough to never forget.

i lied once on ground with fireaxe in hands, zomb was going on run onto me, jumped, and i was dead - one hit death also - i had really good condition AND helmet!

Same happend to me at the NWA fire station. Healthy status and pristine clothes and helmet.

Same thing happened to me as well. I had mosin, m4a1 with all upgrades and a LOT of mags, all decked out with spray paint. One zombie came out of nowhere and hit me. I was hydrated, energized and healthy - all green bars were there. I had a ballistic helmet on and I still died from one hit. I did not go unconscious or anything just instant you are dead. I think I will wait till this gets fixed I spent the entire day getting gear.

This is not a bug. If the unlikely event of a zombie hitting your head happens, it's an instant death for the player. If you're lying on the ground, the zombie is more likely to hit your head.

I think if you're standing, only jumping zombies can hit your head, but I'm not 100% sure about that.

This has happened to me a few times. @Exstinguo: I have been head hit while standing erect (and running even) and killed instantly, so it can happen. Its much more likely though if you are prone or crouched, so if you crawl or kneel a lot, wear a helmet, if you go around in a beret or bonnie cause it looks cool, be aware of the consequences. Also, Zombies aren't very nimble, get in the habit of moving around quickly to dodge their swings and lunges. I've fought 3 zom's at once without taking a scratch just by staying in motion and running in circles.

The fact that it's much more likely to happen if you're prone tells me that this is not a bug. I have only been one-hit-killed once, and that was when I was lying on the ground.

In the last update they noted in the change log that kneeling players are at very high risk for damage to the head from zombies, but I have also had some experience with ridiculous amounts of zombie damage. I was at nearly full health and still healing and a zombie hit me once and sent me 5 damage messages. One said my leg was in pain, one said my arm might be broken, and 3 said my arm was in extreme pain. The next hit from the zombie killed me instantly. I had also been wearing a ballistics helmet and I believe an anti-stab vest.

This just happened to me as well. It was just after a server restart at the small military base south of the NW air field. I was running away from a zombie and equipping my fire axe when I got the black "you are dead" screen.

I am absolutely sure that I had 100% health as I had the green energized, hydrated and healthy buffs (and had just finished healing about 10 min prior to server restart). I could see my surroundings in full color and had no reason to believe anything was wrong with my characters health.
Also I have noticed that the U.K Assault vest seem to get ruined after one hit from a zombie, and in about 25% of the times, all the stuff you keep in it gets ruined as well. I understand that it takes most of the damage most of the times but its the "all or nothing" that makes me wounder if its supposed to be this way?

It would be REALLY great if this one hit kill thing could be fixed. It is totally unbalanced to take one single swat from a zombie and be instantly dead. This has happened to me a bunch of times now, and it happens as often standing fully erect, even with a helmet on as not. It's a huge downer to put days of play into a character and get really nice gear and then be killed from one lucky hit by a zombie. ALSO, and maybe this is a separate issue, but the damn zombies are glitching so badly that even ones you've put 3 rounds into are killing us. They NEED to be fixed. Its not fun to die from one hit by something that can run through walls to get at you, run through a hail of bullets to get at you, it turns the game into a completely unwinnable nonfun waste of time.

One point to note here is that there is a bug with the ballistic helmet.
In its current implementation the ballistic helmet does not provide any shock protection.
I don't think it has been fixed yet as the status is still "assigned". see issue
http://feedback.dayzgame.com/view.php?id=8558
So even if you think your head is nicely protected, against a blow from a zombie, it's not.

sometimes i kill a zombie with one hit with bare knuckles!! why shouldnt am zombie couldnt also do?

I just ran into the same issue. I got aggro'd by a normal zombie, and since I was holding a weapon I had to drop it and get out my axe. In this situation, most of the time there is no way around getting hit at least once with the zombie, since you can't move for a brief period of time. Well, normally this is no problem, but this time the zombie hit me once and I died instantly.

I was at full health, and had a hard hat on. And I'm sure that I wasn't killed by another player.

I don't think this is expected behavior as someone else said. One-hit kill zombies just wouldn't make sense with how the mechanics currently work with getting a melee weapon out.

Another thing that might be notable is that I spawned close enough to my body that I could run back. When I got back there, the zombie that killed me was standing on my body, and was bugged out such that it wouldn't see or attack me until I started punching it. Once I killed it, I could see my body there with all of the items I had when I died, but I couldn't access the inventory to loot, or check the body's pulse or anything like that. Not sure if that might indicate anything about what the bug is.

Happend to me too.it might be somthing that is suposed to be in the game?

This is why it happens: Bone Condition Stat - https://www.youtube.com/watch?v=wky22FdMY5w&list=UUEaZAoRquVbDm7-8u1qastw

Hello ZG_Ganja,

The current iteration of melee damage is not the final version and will be reworked/balanced by the dev team as the project comes along.

Regards,
JStewart