The 1927 U.S. National Championships (now known as the US Open) was a tennis tournament that took place on the outdoor grass courts at the West Side Tennis Club, Forest Hills in New York City, United States. The women's tournament was held from August 22 until August 30 while the men's tournament ran from September 12 until September 17. It was the 47th staging of the U.S. National Championships and the fourth Grand Slam tennis event of the year. This edition saw the introduction of seedings in the draw which were meant to prevent the best players from meeting each other in the early rounds of the tournament.

Champions

Men's singles

🇫🇷 René Lacoste defeated 🇺🇸 Bill Tilden 11–9, 6–3, 11–9

Women's singles

🇺🇸 Helen Wills defeated 🇬🇧 Betty Nuthall 6–1, 6–4

Men's doubles

🇺🇸 Bill Tilden / 🇺🇸 Frank Hunter defeated 🇺🇸 Bill Johnston / 🇺🇸 R. Norris Williams 10–8, 6–3, 6–3

Women's doubles

🇬🇧 Kitty McKane Godfree / 🇬🇧 Ermyntrude Harvey defeated 🇬🇧 Betty Nuthall / 🇬🇧 Joan Fry 6–1, 4–6, 6–4

Mixed doubles

🇬🇧 Eileen Bennett / 🇫🇷 Henri Cochet defeated 🇺🇸 Hazel Hotchkiss Wightman / 🇫🇷 René Lacoste 6–2, 0–6, 6–3