You might be interested in the section of our FAQ which deals with this subject, which has several great answers, including:
/u/commiespaceinvader's replies to Did the nazis make any contribution to the medical field? and Did the Axis medical experiementation (Nazi and Japanese) give any significant advances? Was the main motivator behind it research or cruelty? and
/u/estherke's reply to Did Josef Mengele Ever Succeed in Any of His Experiments?