The 1978 US Open was a tennis tournament played on outdoor hard courts at the USTA National Tennis Center in New York City in New York in the United States. It was the 98th edition of the US Open and the third Grand Slam tennis event of the year. The tournament was held from August 28 to September 10, 1978, and the singles titles were won by Jimmy Connors and Chris Evert. This was the first year the US Open was played at the National Tennis Center in Flushing Meadows after having been organized at the West Side Tennis Club venue in Forest Hills since 1915. It was also the first time the tournament was played on hard courts, as opposed to much of its history on grass and a brief stint, from 1975 through 1977, on clay.

Seniors

Men's singles

🇺🇸 Jimmy Connors defeated 🇸🇪 Björn Borg, 6–4, 6–2, 6–2

Women's singles

🇺🇸 Chris Evert defeated 🇺🇸 Pam Shriver, 7–5, 6–4

Men's doubles

🇺🇸 Bob Lutz / 🇺🇸 Stan Smith defeated 🇺🇸 Marty Riessen / 🇺🇸 Sherwood Stewart, 1–6, 7–5, 6–3

Women's doubles

🇺🇸 Billie Jean King / 🇺🇸 Martina Navratilova defeated 🇦🇺 Kerry Melville Reid / 🇦🇺 Wendy Turnbull, 7–6, 6–4

Mixed doubles

Betty Stöve / Frew McMillan defeated 🇺🇸 Billie Jean King / 🇦🇺 Ray Ruffels, 6–3, 7-6

Juniors

Boys' singles

🇸🇪 Per Hjertquist defeated 🇸🇪 Stefan Simonsson, 7-6, 1-6, 7-6

Girls' singles

🇺🇸 Linda Siegel defeated 🇦🇷 Ivanna Madruga, 6–4, 6-4