Removing joining lines?

[TEK81]

I have just copied, and mirrored half of a human head model, in hope that I could place the two pieces together and end up with a rather nice looking head.
After doing so however, I am left with an unsightly join line running though it.
Can anyone tell me how I can go about removing it?

Thanks for any help.
Tek:)

forgot to add, I am using max5

[kuman]

you need to weld the two halves together to get rid of that joint line