Takeshi Hirayama (平山 雄, Hirayama Takeshi, January 1, 1923 – October 26, 1995) was a Japanese cancer epidemiologist and anti-tobacco activist who served as the chief of the epidemiology division at the National Cancer Center [ja] in Tokyo from 1965 until 1985.

[1] When he was three, his father, Tohshi Hirayama, became professor of surgery at Manchuria Medical College, which led to him and his family moving to the city of Harbin in China.

[2] In 1981, Hirayama published a study of 265,000 people which found an association between exposure to secondhand smoke and an increased risk of lung cancer.

[8][7] In 1984, Hirayama published a cohort study of 265,118 adults which reached conclusions similar to those of his 1981 study, namely, that non-smoking wives of smoking husbands were at an increased risk of lung cancer and ischemic heart disease.

[10][11] Hirayama also studied the relationship between green and yellow vegetable consumption and a decreased risk of certain cancers.