The Lightweight Boat Races are a series of annual rowing races between men's and women's lightweight crews representing the University of Oxford and the University of Cambridge.

The first men's race took place in 1975, being joined by the women's race in 1984. Both races are currently held on the 4.2-mile (6.8 km) Championship Course from Putney to Mortlake, although they previously formed part of the Henley Boat Races, along with various other rowing races between the two universities, including the openweight women's Boat Race. Members of both teams are traditionally known as blues or half blues and each boat as a Blue Boat. Competitors at the events have gone on to compete at international and Olympic levels.

Richard Bates, a Cambridge undergraduate, organised a Boat Race between lightweight men's crews of Oxford and Cambridge universities in 1975, to take place at Henley-on-Thames. The race was joined by the openweight women's Boat Race two years later, thus forming the Henley Boat Races. The first lightweight women's boat race took place at the event in 1984.^[3] Reserve races have taken place since 2000 (except 2010–2015) for the lightweight men (Nephthys vs Granta) and in some years since 2012 for the lightweight women (Tethys vs CUWBC Lightweight Reserves).

In 2019, the lightweight men's race moved to the Championship Course from Putney to Mortlake, where it has been held since. The lightweight women's race made the same move the following year in 2020.^[1]

For the men's race the average weight of the crew must not exceed 70 kilograms (154.3 lb; 11 st 0.3 lb), with no rower weighing over 72.5 kilograms (159.8 lb; 11 st 5.8 lb). For the women's race, no rower can exceed 59 kilograms (130.1 lb; 9 st 4.1 lb).

The races receive annual press coverage,^{[4][5][6][7][8]} and competitors from both Universities have gone on to compete at international and Olympic levels.^{[9][10][11][12]}

The history of the results of the races are as follows.^{[13][14][15][16][17]}

• Cambridge: 30 wins
• Oxford: 20 wins

• Cambridge: 24 wins
• Oxford: 17 wins

• Oxford: 11 wins (inc. 3 R/O)
• Cambridge: 8 wins

• Cambridge: 5
• Oxford: 2

Raced on the Friday before the main event in a 4+ in 2012, and incorporated into main race day in 2016.

• The Boat Race
• Henley Boat Races

• Official website