The collection is from the estate of Jane Borson Sellers, a lifelong friend of Hefner for almost 80 years.
Chicago firm Potter & Potter Auctions will offer the archive across a dozen lots as part of its Fine Books and Manuscripts Sale on July 28.
Hefner met Borson Sellers at Steinmetz High School in Chicago in the early 1940s and maintained a close relationship with her over the course of his life.
Highlights of the sale include a collection of 60 letters from high school, a cartoon drawn by Hefner and a 1944 signed high school senior class sepia print photograph.
Gabe Fajuri, president at Potter & Potter Auctions, said: "This archive reveals the private, personal, pre-Playboy side of Hugh Hefner – something very few, if any, of his millions of fans got a glimpse of. Hefner lived on a grand scale, and was constantly in the spotlight, yet the letters he exchanged with his high school classmate show he was not just larger-than-life he could also be down to earth."
