Would i need a new sim card?

So i'm getting an iphone 5 tm and i have the mytouch 4g slide and do i need a new sim card to fit the iphone or can i still have ny same one?

Most likely yes. Iphones use different sized sim cards then regular phones. Not to mention the Mytouch 4g slide is fairly old and probably has a regular sized sim card. There are 3 sizes of sim card the biggest is Regular
second biggest is Micro
and smallest is Nano

I'm betting that your mytouch is either regular or micro because nano is the newest. And also the iphone 5 uses nano. So if you have a nano sim card then you are good to go and you can just put it it. But if you don't then you are going to have to buy a different sim card but they might give it to you for free.

I just checked it out and the Mytouch 4g does have a regular sim card so you will need a nano one. So no you can't because it won't fit.