The Boat Race is an annual set of rowing races between the Cambridge University Boat Club and the Oxford University Boat Club, traditionally rowed between open-weight eights on the River Thames in London, England. It is also known as the University Boat Race and the Oxford and Cambridge Boat Race.

The men's race was first held in 1829 and is the second oldest inter-university sporting event in the world. It has been held annually since 1856, except during the First and Second World Wars (although unofficial races were conducted) and the COVID-19 pandemic in 2020. The first women's event was held in 1927, and the Women's Boat Race has been an annual event since 1964. Since 2015, the women's race has taken place on the same day and course, and since 2018 the combined event of the two races has been referred to as "The Boat Race".

The Championship Course has hosted the vast majority of the races. Covering a 4.2-mile (6.8 km) stretch of the Thames in West London, from Putney to Mortlake, it is over three times the distance of an Olympic race. Members of both crews are traditionally known as blues and each boat as a "Blue Boat", with Cambridge in light blue and Oxford in dark blue. As of the 2025 race, Cambridge has won the men's race 88 times to Oxford's 81 times, with one dead heat, and has led Oxford in cumulative wins since 1930. In the women's race, Cambridge has won the race 48 times to Oxford's 30 times, and has led Oxford in cumulative wins since 1966. A reserve boat race has been held since 1965 for the men and since 1966 for the women.

For a majority of time, over 250,000 people watch the race from the banks of the river. In 2009, a record 270,000 people watched the race live. The race is broadcast internationally on television; in 2014, 15 million people watched the race on television.

The tradition was started in 1829 by Charles Merivale, a student at St John's College, Cambridge, and his Old Harrovian school friend Charles Wordsworth who was studying at Christ Church, Oxford. The University of Cambridge challenged the University of Oxford to a race at Henley-on-Thames but Oxford won easily. Oxford raced in dark blue because five members of the crew, including the stroke, were from Christ Church, then Head of the River, whose colours were dark blue.

The second race was in 1836, with the venue moved to a course from Westminster to Putney. Over the next two years, there was disagreement over where the race should be held, with Oxford preferring Henley and Cambridge preferring London. Following the official formation of the Oxford University Boat Club, racing between the two universities resumed in 1839 on the Tideway and the tradition continues to the present day, with the loser challenging the winner to a rematch annually.

Since 1856, the race has been held every year, except for the years 1915 to 1919 due to World War I, 1940 to 1945, due to World War II, and in 2020 due to COVID-19 pandemic policy.

The race in 1877 was declared a dead heat. Both crews finished in a time of 24 minutes and 8 seconds in bad weather. The verdict of the race judge, John Phelps, is considered suspect because he was reportedly over 70 and blind in one eye. Rowing historian Tim Koch, writing in the official 2014 Boat Race Programme, notes that there is "a very big and very entrenched lie" about the race, including the claim that Phelps had announced "Dead heat ... to Oxford by six feet" (the distance supposedly mentioned by Phelps varies according to the telling).