There was a ton of them released from the late 1950's to about 1965. It was before the rating code came into effect, but nudity could be snuck into a film if it was filmed at a nudist camp and passed off as a "documentary".
There are quite a few floating around youtube last time I checked. Here's a couple:
Diary of a Nudist: youtube.com/watch?v=FGud4qJJa9o
Nude on the Moon: youtube.com/watch?v=czxgLpcFovg (hilarious)
And here's one I downloaded for fear it might get deleted -- The Raw Ones -- made in 1965 and one of the few featuring lots of full frontal nudity. Not the best rip, unfortunately:
http://www108.zippyshare.com/v/bvydLQHG/file.html