High School Old Boys is a rugby union football club based in Christchurch, New Zealand.

While many members are former CBHS students, High School Old Boys RFC is an open club accepting both male and female players.

This is generally shortened to "High School Old Boys" (HSOB) and the club is commonly referred to simply as "Old Boys" or the "Polar Bears" due to their full white playing uniform and notoriously cold home fields.

The High School Old Boys clubrooms are located in Hagley Park adjacent to the Bob Deans Playing Fields on North Hagley Park, 12 Riccarton Avenue, Christchurch Old Boys colours are: White jersey, white shorts and black socks with blue tops A number of New Zealand representatives, called All Blacks, have been selected for international duties while affiliated to the club.

In 2022 HSOB Rugby also had their first Black Ferns (NZ Women's) player with World Cup winning Full Back Renee Holmes