Unit Ei 1644

Unit Ei 1644 (Japanese: 栄1644部隊) — also known as Unit 1644 — was a laboratory and one of the water purification centers established under control of the Epidemic Prevention and Water Purification Department. It was established in 1939 in Japanese-occupied Nanking as a satellite unit of Unit 731.

An anonymous researcher, who claims he was attached to Unit 1644, says that it regularly carried out human vivisections as well as infecting humans with cholera, typhus, and bubonic plague. The researcher and his family had not yet reached an agreement about releasing his name.