Most of us heard about the horrible experiments on humans of the Nazis done by doctor Mengele.
But the Nazis weren’t alone in conducting cruel experiments on humans.
One of the lesser known atrocities of the 20th century was committed by the Imperial Japanese
Army’s Unit 731. Some of the details of this unit’s activities are still uncovered. This webpage was set up to
collect and organize the information known to date about Unit 731 and present it to anyone interested.
For 40 years, the horrific activities of "Unit 731" remained one the most closely guarded
secrets of World War II. It was not until 1984 that Japan acknowledged what it had long denied - vile experiments
on humans conducted by the unit in preparation for germ warfare.
Deliberately infected with plague, anthrax, cholera and other pathogens, an estimated 3,000 of
enemy soldiers and civilians were used as guinea pigs. Some of the more horrific experiments included vivisection
without anesthesia and pressure chambers to see how much a human could take before his eyes popped out.
Unit 731 was set up in 1938 in Japanese-occupied China with the aim of developing biological
weapons. It also operated a secret research and experimental school in Shinjuku, central Tokyo. Its head was
Lieutenant Shiro Ishii.
The unit was supported by Japanese universities and medical schools which supplied doctors and
research staff. The picture now emerging about its activities is horrifying. According to reports never officially
admitted by the Japanese authorities, the unit used thousands of Chinese and other Asian civilians and wartime
prisoners as human guinea pigs to breed and develop killer diseases.
Many of the prisoners, who were murdered in the name of research, were used in hideous
vivisection and other medical experiments, including barbaric trials to determine the effect of frostbite on the
To ease the conscience of those involved, the prisoners were referred to not as people or
patients but as "Maruta", or wooden logs. Before Japan’s surrender, the site of the experiments was completely
destroyed, so that no evidence is left.
Then, the remaining 400 prisoners were shot and employees of the unit had to swear secrecy. The
mice kept in the laboratory were then released, which could have cost the lives of 30,000 people, since the mice
were infected with the bubonic plague, and they spread the disease.
Few of those involved with Unit 731 have admitted their guilt.
Some caught in China at the end of the war were arrested and detained, but only a handful of
them were prosecuted for war crimes.
In Japan, not one was brought to justice. In a secret deal, the post-war American administration
gave them immunity for prosecution in return for details of their experiments.
Some of the worst criminals, including Hisato Yoshimura, who was in charge of the frostbite
experiments, went on to occupy key medical and other posts in public and private sectors.