1979 Japan Open Tennis Championships

The 1979 Japan Open Tennis Championships, also known by its sponsorship name Hit-Union Japan Open Tennis Championships, was a combined men's and women's tennis tournament played on outdoor clay courts in Tokyo, Japan that was part of the Colgate Series and the Volvo Grand Prix circuit. The tournament was held from 22 October through 28 October 1979. Terry Moor (ninth-seeded) and Betsy Nagelsen won the singles titles.

Men's singles
🇺🇸 Terry Moor defeated 🇺🇸 Pat Du Pré 3–6, 7–6, 6–2
 * It was Moor's 1st title of the year and the 1st of his career.

Women's singles
🇺🇸 Betsy Nagelsen defeated 🇺🇸 Naoko Sato 6–1, 3–6, 6–3
 * It was Nagelsen's 2nd title of the year and the 2nd of her career.

Men's doubles
🇦🇺 Colin Dibley / 🇺🇸 Pat Du Pré defeated 🇦🇺 Rod Frawley / Francisco González 3–6, 6–1, 6–1

Women's doubles
🇺🇸 Betsy Nagelsen / 🇺🇸 Penny Johnson defeated 🇨🇳 Yu Li-Chiao / 🇨🇳 Chen Chuan 3–6, 6–4, 7–5