My 1995 Saturn leaked basically all the anti-freeze out of it. What could it be?

It could be the water pump. You could borrow a pressure tester from auto zone for free. If you can not see where it's coming from then you may have to remove a few parts. If it's the water pump. You have to remove some of these parts to chance anyway. I would take the belt and water pump pulley off you should be able to see the pump body them. After you remove the belt and pulley then pressure check the coolant system if the pump is leaking them with the parts removed. You should be able to identify the leak

Was the smoking (white smoke) if so a head or intake gasket could be leaking otherwise the leak is from the water pump or still could be head or intake gaskets, of course cracks and hoses leaking out of the motor too. Check you oil and make sure it does not have a milky look.

Ok guys thanks for your help. My son did a radiator flush..took off the reseviour and cleaned it really good. Then he replaced the water pump and Thermastat. The belt was already new and the hoses are all good. We ran around all day and no over heating or leakage. I'm going to post a new question I hope some one can help me with. The Service Engine Soon Light comes on when the Fan kicks on to cool the car off. When I shut the car off and restart later it's not on. Doesn't come on when I go on short trips just on hot days or long trips when the fan comes on to cool the car back off. It doesn't blink and it always goes off and stays off till that fan kicks on. This did this before the repairs. I went to Auto Zone to have them check the codes, however they said they couldn't because it is a 1995. Any clues guys. Sorry so long and thanks again.