|Intro||South African tennis player|
|Is||Athlete Tennis player|
|From||United States of America South Africa|
|Birth||18 December 1956, Port Elizabeth, South Africa|
Yvonne Vermaak (born 18 December 1956) is a former tour tennis player who represented her native South Africa.
Vermaak's best result was reaching the semi-finals of the 1983 Wimbledon Championships, defeating Virginia Wade in the quarter-finals.
In 1977 she won the All England Plate, a competition for players who were defeated in the first and second rounds of the Wimbledon singles competition. In the final she defeated Sue Mappin in straight sets.
Late in her playing career, Vermaak became an American citizen.
Vermaak played USTA Master's tennis. Representing Illinois, she was the 1992 Singles Champion of the USTA National Women's Indoor Championships in Homewood for 35's. In 1993, Yvonne Vermaak was the 25's Singles Champion, and again she was the 25's Singles Champion in 1994. In 1995, Vermaak moved on to Doubles, winning the 25's and 35's doubles with her partner Ann Kiyomura-Hayashi of California. The 1995 Championships was Vermaak's last USTA Championships win.
Singles 6 (4–2)
|Win||1.||4 June 1977||Beckenham, England||Grass||Michelle Tyler||6–4, 5–7, 6–1|
|Loss||2.||17 September 1978||San Antonio, Texas, USA||Hard||Stacy Margolin||5–7, 1–6|
|Loss||3.||11 January 1982||Fort Myers, Florida, USA||Hard||Lee Duk-hee||0–6, 3–6|
|Win||4.||6 March 1983||Palm Springs, California, USA||Hard||Carling Bassett||6–3, 7–5|
|Win||5.||19 September 1983||Salt Lake City, Utah, USA||Hard||Felicia Raschiatore||6–2, 0–6, 7–5|
|Win||6.||16 September 1984||Salt Lake City, Utah, USA||Hard||Terry Holladay||6–1, 6–2|
Doubles 7 (4–3)
|Titles by surface|
|Loss||1.||16 June 1978||Chichester, England||Grass||Michelle Tyler|| Janet Wright
|6–3, 3–6, 4–6|
|Loss||2.||19 July 1981||Kitzbühel, Austria||Clay||Elizabeth Little|| Claudia Kohde-Kilsch
|Win||3.||9 May 1982||Perugia, Italy||Clay||Kathy Horvath|| Billie Jean King
|2–6, 6–4, 7–6|
|Loss||4.||6 November 1982||Hong Kong||Clay||Jennifer Mundel|| Laura duPont
|2–6, 6–4, 5–7|
|Win||5.||19 September 1983||Salt Lake City, Utah, USA||Hard||Cláudia Monteiro|| Amanda Brown
|6–1, 3–6, 6–4|
|Win||6.||5 February 1984||Indianapolis, Indiana, USA||Hard||Cláudia Monteiro|| Beverly Mould
|6–7, 6–4, 7–5|
|Win||7.||6 April 1984||Miami, Florida, USA||Clay||Patricia Medrado|| Kate Latham