The 1978 German Open was a combined men's and women's tennis tournament played on outdoor red clay courts. The men's tournament was part of the 1978 Colgate-Palmolive Grand Prix circuit, categorized as a four-star event, while the women's tournament was part of the Colgate Series and classified as an A category event. It was the 70th edition of the tournament and took place at the Am Rothenbaum in Hamburg, West Germany, from 15 May through 21 May 1978. Guillermo Vilas and Mima Jaušovec, both first-seeded, won the singles titles.

Finals

Men's singles

Argentina Guillermo Vilas defeated Poland Wojciech Fibak 6–2, 6–4, 6–2

Women's singles

Socialist Federal Republic of Yugoslavia Mima Jaušovec defeated Romania Virginia Ruzici 6–2, 6–3

Men's doubles

Netherlands Tom Okker / Poland Wojciech Fibak defeated Spain Antonio Muñoz / Paraguay Víctor Pecci 6–2, 6–4

Women's doubles

Socialist Federal Republic of Yugoslavia Mima Jaušovec / Romania Virginia Ruzici defeated West Germany Katja Ebbinghaus / West Germany Helga Masthoff 6–4, 5–7, 6–0

External links