The 1978 New South Wales Open, also known by its sponsored name Marlboro New South Wales Open, was a combined men's and women's tennis tournament played on outdoor grass courts at the White City Stadium in Sydney, Australia. The men's event was part of the 1978 Colgate-Palmolive Grand Prix circuit while the women's event was art of the 1979 Colgate Series.[3] It was the 86th edition of the event and was held from 18 December through 24 December 1978. The singles titles were won by unseeded Tim Wilkison and second-seeded Dianne Fromholtz.[4][5]
| 1978 New South Wales Open | |
|---|---|
| Date | 18–24 December 1978 |
| Edition | 86th |
| Category | Grand Prix (Four star) |
| Draw | 64S/32D (M) |
| Prize money | $100,000 (M) $35,000 (W) |
| Surface | Grass / outdoor |
| Location | Sydney, Australia |
| Venue | White City Stadium |
| Champions | |
| Men's singles | |
 Tim Wilkison[1] | |
| Women's singles | |
 Dianne Fromholtz | |
| Men's doubles | |
| Hank Pfister / Sherwood Stewart[2] | |
| Women's doubles | |
| Lesley Hunt / Sharon Walsh | |
Finals
Men's singles
Tim Wilkison defeated 
Kim Warwick 6–3, 6–3, 6–7, 3–6, 6–2
Women's singles
Dianne Fromholtz defeated Wendy Turnbull 6–2, 7–5
Men's doubles
Hank Pfister / Sherwood Stewart defeated Syd Ball / Bob Carmichael 6–4, 6–4
Women's doubles
Lesley Hunt / Sharon Walsh defeated 
Ilana Kloss / Marise Kruger 6–2, 6–1