The purpose for most of the medical experiementation done on live humans was three-fold.
The first order of business was to use science and technology to create a "superior Arian race". There were medical experiements done in Auschwitz and Ravensbrueck which involved the sterilization of Jewish and Roma women through injections of various substances. The Nazi world-view consisted of a superior race that ruled over all others or simply anhilated all other races. Dr. Joseph Mengle presided over medical experimentation involving twins.
The Nazi "doctors" were looking for tuberculosis cures and so removed the lymph nodes from children and injected them with live tuberculosis bacteria. The Nazis were actually using the starvation diet to calculate just exactly how much food a soldier would need to maintain a healthy stamina to keep up his strength during a war. The work requirements and food rations were methodically recorded by the guards and personnel in charge of food and work details.
At Sachsenhausen, Dachau, Natzweiler, Buchenwald, and Neuengamme, the medical experiements involved various types of infectious diseases and the newly developed sulfa drugs. Women and children were cut on their arms and legs and had various types of dirty things rubbed into the open wounds which were then stitched closed with the contaminants still inside the wound. Raging infections developed as a result. All of this medical experimentation was carefully recorded with the various results dutifully recorded. Some of the experiments involved amputation of limbs followed by quick cauterization of the wound. Then various dirty substances were rubbed into the wound. The purpose for this was two-fold. Could a soldier survive a field amputation and an ensuing infection on the battlefield?
The question now is: "Is it ethical to use the information discovered during this time period of human experimentation?"
At Dachau, the German Air force tested the altitude from which a pilot might survive a parachute jump using a low pressure chamber. Most of the human test subjects did not survive the experiments. Another military test was subjecting the victim to freezing water conditions to the point of hypothermia and then trying to revive the subject. Again, many did not survive. The purpose of these experiments was to determine a safe altitude for the German pilots to eject from a disabled aircraft.
To me the most amazing thing is the complete impunity with which these experiments were recorded. The experiment data were recorded exactly as to the age, gender and weights of the victims. The procedures were recorded exactly as were the various variable conditions of each experience.
Two excellent sources are:
Anatomy of the Auschwitz Death Camp edited by Yisrael Gutman and Michael Berenbaum
Children of the Flames: Dr. Josef Mengele and the Untold Story of the Twins of Auschwitz by Lucette Matalon Lagnado and Sheila Cohn Dekel. Penguin USA, 1992.
There are a few victims of medical experimentation still alive today in Russia and in the U.S.