I hid my thief (dual wielding katana and longsword) in went behind the creature (is this necessary btw?) and attacked. Nothing.
I tried this several times with no results.

Is there THAC0 bonuses or penalties when backstabbing? Must i reach a certain level to backstab?
What is this backstab multiplyer and why is it defferent to diiferent thiefs? Because of exp lvl?

Generally what does backstabbing depends on?

As the word makes clear - you have to stand "behind the back" of your victim. The only thing that depends on level up is the amount of damage your thief deals out:

lvl-1 to 4: 2x damage
lvl-5 to 8: 3x damage
lvl-9 to 12: 4x damage
after lvl-13: 5x damage

You have to make sure that your char is still on stealth when he tries to backstab. If you handle it badly (or your thief has poor stealth) he steps out of the shadow first and gets only single damage then. I recommend to use the <F2> function to attack from shadow, it can be easier then ;)

Btw: The higher the stalth abilities are, the longer will your char remain hiden after stepping out of the dark.

Thank you for Table, but i when followed your instuctions i didnt succeed even oce. (I was in hid in shadows (hide in sh: 110) AND was behind victim. And did it lot of times. nothing. I was dual wielding katana and sword. Maybe this should be dagger only?
And i guess character must be hostile to you.
Because to attack neutral or positive character sword icon must be selected. But selecting it automatically disables hiding in shadows.
BUT once again my thief attacked hostile creature when hid in shadows FROM behind several times, and nothing...

There are a number of weapons that back stabbing cannot be done with. IIRC a longsword is one of them. Try removing the longsword and just back-stabbing with the katana or dagger.

You can backstabb with a longsword, shortsword, dagger, scimitar/ ninja-to/ wakizashi, just like with a katana.

And for backstabbing: It almost always worked for me ... but I enjoyed years of training playing thieves in BG-1 and BG-2 ;)

Kasio, what were you backstabbing? Several creatures in Bg cannot be backstabbed. For example: Golems, Dragons and Beholders. Try it on a humanoid, maybe then it will work.

Also, the game will not notify you of a succesful backstab as far as I can remember. You just have to look at the amount of damage and see if it is that extraordinary that you can call it a backstab. I'm not sure about this, gonna check it when I play this game again.

I have a thief (Luthien) in my party with Cutthroat, hide in shadow at 145%, I hide her in the shadows, sneak behind the enemy and want to backstab but I receive the message: Backstab damage seems to have failed.
What's da prob?

Igneous, when you backstab, you see in the messageboard Backstab Triple/Quantiple Damage and then how many damage youdit to the enemy.

[This message has been edited by Headbanger (edited May 08, 2001).]

That´s the kinda response I got when I wanted to backstabb a beholder once ... however, you still get the first attack then I think.

Ah... My mind was emtpy with Bg and full of Torment. Haven't played it for two weeks and I already make mistakes ;) Think I have to let a priest examine that damn amnesia of me soon...

Why don't you try goin behind a regular victim(someone not important) and then pause the game, single wield and click attack on the target and then unpause.
Hope this helps

i always use the short sword of backstabbing for backstabs... dunno if its the best.. but it sure fits the title...