the lost tales canon or not?

I've heard different opinions on this matter. some say it's perfectly canon. some say it's not. so tell me if it is canon, and why.…

Some parts of it are Canon some parts arn't. Parts of Lost Tales that directly contradict with something stated as true in the Sil or LOTR would not be considered Canon as they are lesser place. However I personally have no problem accepting the LT as a primary source of Canon information provided that it doesn't contradict any other more "reliable" information.

well, the parts about the istari and so one are good. but the moast crazy sfuff happen in that book. on an other forum, the member Traya said that Ectelion killed three balrogs in that book. I have no memory of that. But if it is so, well than I'm astonished. how can he? he just an elf. everybody who has tried to take on a balrog has died. Fëanor, Gandalf (well he returned but...) and Echtelion himself when he killed Gothmog. so those things. are they "canon"?

Do you mean The Book of Lost Tales? 'Cause they are definitely not canon, at least in relation to the later stories, as they represent the very idea-germs which later resulted in The Silmarillion.

I mean both The book of the lost tales, and the Unfinished tales. sorry mixed them up. only have the swedish versons see and they have different names so I picked the wrong name it seems. but both of them then. is the unfinished tales book canon?

Ah, I see.

Well, to answer your question....I'd say yes.
They represent Tolkien's mature ideas, but were just never truly finished.