The 1978 Rothmans Canadian Open was a tennis tournament played on outdoor hard courts at the National Tennis Centre in Toronto in Canada that was part of the 1978 Colgate-Palmolive Grand Prix and of the 1978 WTA Tour. The tournament was held from August 14 through August 20, 1978.
Eddie Dibbs defeated José Luis Clerc 5–7, 6–4, 6–1
- It was Dibbs' 4th title of the year and the 18th of his career.
Regina Maršíková defeated Virginia Ruzici 7–5, 6–7, 6–2
- It was Maršíková's 2nd title of the year and the 3rd of her career.
Wojciech Fibak / Tom Okker defeated Colin Dowdeswell / Heinz Günthardt 6–3, 7–6
- It was Fibak's 6th title of the year and the 33rd of his career. It was Okker's 6th title of the year and the 77th of his career.
Regina Maršíková / Pam Teeguarden defeated Chris O'Neil / Paula Smith 7–5, 6–7, 6–2
- It was Maršíková's 3rd title of the year and the 4th of her career. It was Teeguarden's only title of the year and the 2nd of her career.