The 1978 Australian Open was a tennis tournament played on outdoor grass courts at the Kooyong Lawn Tennis Club in Melbourne, Australia and was held from 25 December 1978 to 3 January 1979. It was the 67th edition of the Australian Open and the fourth Grand Slam tournament of the year. The singles titles were won by Argentinian Guillermo Vilas and Australian Chris O'Neil.

Seniors

Men's singles

🇦🇷 Guillermo Vilas defeated 🇦🇺 John Marks, 6–4, 6–4, 3–6, 6–3

Women's singles

🇦🇺 Chris O'Neil defeated 🇺🇸 Betsy Nagelsen, 6–3, 7–6(7–3)

Men's doubles

🇵🇱 Wojciech Fibak / 🇦🇺 Kim Warwick defeated 🇦🇺 Paul Kronk / 🇦🇺 Cliff Letcher, 7–6, 7–5

Women's doubles

🇺🇸 Betsy Nagelsen / Renáta Tomanová defeated 🇯🇵 Naoko Sato / 🇦🇺 Pam Whytcross, 7–5, 6–2

Mixed doubles

This event was not held from 1970 until 1985.