Javascript setInterval function to clear itself?

myInterval = setInterval(function(){
     MyFunction();
},50);

function MyFunction()
{
    //Can I call clearInterval(myInterval); in here?
}

The interval's not stopping (not being cleared), if what I've coded above is fine then it'll help me look elsewhere for what's causing the problem. Thanks.

EDIT: Let's assume it completes a few intervals before clearInterval is called which removes the need for setTimeout.