Medical

My father was adopted and never found his birth parents. It was a 'military adoption' and I really have no clue how to go about finding out how to get into the records. Actually, I have no idea where to start to try to find them. I have several medical problems that are obviously from my father's side, and I really need to know the medical history back there !! All I know (and I've asked) is the general background..we have no names, no anything. Dad was adopted in the 50's, and I've been told that since it was then, and a military adoption that its going to be quite difficult to get into those records. Do you have any advice as where I can start? Thx :)