Isao Arita (born 1926) is a Japanese physician, virologist and vaccination specialist who headed the World Health Organization (WHO) Smallpox Eradication Unit in 1977–85. During this period, smallpox became the first infectious disease of humans to be eradicated globally. For this work, he and his colleagues were awarded the Japan Prize in 1988. He also advised the successful programme to eradicate poliovirus from the Western Pacific region.