Sex Histories Part I (性史第一輯; Xìngshǐ dìyījí, often simply called Sex Histories, 性史; Xìngshǐ) is a 1926 book by Chinese philosopher and sexologist Zhang Jingsheng.

[1] On 2 February 1926, Zhang published an article in the Beijing periodical Jingbao Fukan titled "The Best Pastime for a Winter Vacation: An Announcement for the Colleagues of the Eugenics Society", soliciting detailed stories of readers' sexual experiences.

Seven were featured in the book, with Zhang analyzing and commenting on them as case studies.

Large numbers of pirated copies boosted its circulation beyond the initially small print runs.

[1][2] A large number of unauthorized parodies and knock-offs of Sex Histories were produced by various authors following the book's release, many of which were brazenly pornographic parodies or excerpts from earlier erotic texts.