As this is not a clear question, there are multiple possibilities. could be just about anything. Put on a lift and check for play in wheels (bearings?), and looseness in steering / suspension components. (Or take into a shop)
usually a loose bolt
Depends on where the noise is whats making the noise. Can you be more descriptive of where and what?
The batter is low
There are a number of causes for a rattling noise that occurs in a car. These include low oil and an engine that is faulty or going out.
tie rod
sounds like the cv joints need replaced
it may be your tire alignment. your tires may need to be re-aligned. a couple of months ago my car started making a rattling noise when we would go about 70 mph on the highway. we found out are tires needed to be aligned again.
mine needed power steering fluid
the car may be low on power steering fluid
your Imagination.... :)
bad transfer case
could be your wheel bearings