stay hidden of them and shoot them when they dont see you.
If possible get Fatman/Fatboy and shoot for there head once shot and not dead run up not to close and shoot with shot gun!

and another way is
step 1.) find a deathclaw.
step 2.) have a gatling laser (particularly vengeance)
step 3.) unleash total hell.
this was suggested on gamespot.com under forums along with others in
:"my way to kill a deathclaw" under fallout3 forums.

Deathclaws are reptiles that stand roughly 10 feet tall, with an extremely resistant thick skin, powerful muscle and bone structure as well as razor-sharp claws, resulting in their moniker. Their build gives them incredible speed, resiliency and strength in close combat, making them an extreme threat at all times.

Baby Deathclaws are infantile deathclaw offspring, found all around the West Coast.

Prolly just drop a MIRV on it. Best method ever.

I just ran into a my first Deathclaw yesterday (8-30-10) It was easier than I thought.

I just drop mines until I cripple the legs of the deathclaw for it can't run anymore and do those attacks that look like hes gonna give you a hug not just an ordinary a lethal hug. Once the deathclaw is crippled you can kill him by just shooting them with any weapon

Use the dart gun to cripple him then finish him off with any powerful weapon. Same with giant radscorpions.

Also if you have a high level you can use your dog called dogmeat to fight him off cause he becomes resistant later on when you reach a higher level

Instead of wasting so much valuable ammo such as Mini Nukes, why don't you buy (or create) Bottlecap Mines? Drop them ahead of you, stay hidden and perform a Sneak Attack on the Deathclaw. Of course he won't die instantly, and will sprint towards you - arms wide open. He will then step on the Bottlecap Mine, lose a lot of health (it has a damage of about 300 and something) and stop running for one second because of the explosion. Aim at his head and shoot with no mercy.
Dogmeat is an effective alternative. He will draw attention to the Deathclaw, and you'll perform a Sneak Attack on him (always do that if possible). Imediately after that, just shoot his head off. If you have the Auto Axe or it's variant, the Man Opener, use it against him non stop, while he attacks Dogmeat (and remember to give your dog a stimpak so that he doesn't die).
A weapon i find effective against these demons is the Alien Disintegrator, which has a damage of about 69 (max is 70, i think).
Don't use the Minigun, cause it will drain his health slowly, and you'll waste ALOT of ammo (ammo= money).
So remember, Sneak Attack and never use the Minigun.
I believe using the MRIV or Fat Man is a waste of money (unless you're REALLY desperate)and reduction of the weapon's durability. Remember you gotta make sure every weapon you got is in good condition.

Actually, the Dart Gun is the best option

well am maxed levul to i wear power armour and roast the shit out of it or if you have dogmeat hes invicble in my game so

interesting

Easiest way: have Fawkes as your companion.