Noguchi Hideyo (野口 英世, 1876-1928) is a prominent Japanese bacteriologist who discovered the agent of syphilis disease in 1911.

He was born in Fukushima in 1876 under the name Noguchi Seisaku. When he was one and a half years old he fell down into a fireplace and got a burn injury on his left hand. In 1883 he entered Mitsuwa elementary school. Thanks to the generous contribution from his teacher Kobayashi and his friends, he was able to receive surgery on his badly burned left hand. He recovered about 70% of mobility and functionality of his left hand through the operation. He made the decision to become a doctor and help those in need. Seisaku then apprenticed himself to Dr. Watanabe, the same doctor who had performed surgery on his hand. He passed the exam to practice medicine when he was twenty years-old.

In 1898 he changed his name to Noguchi Hideyo.

In 1900 he moved to United States, where he got a job as a research assistant. At this time his work concerned poisonous snakes.

In 1928, he died while he was working on yellow fever in Africa.

His portrait has been printed on Japanese 1000 yen bill since 2004.