Mercedes María Paz (Spanish pronunciation: [meɾˈseðes maˈɾi.a ˈpas]; born 27 June 1966) is a former professional tennis player from Argentina. She won three singles titles on the WTA Tour and reached a career-high ranking of world No. 28 in April 1991. Her best Grand Slam result was the fourth round at the 1986 French Open and the 1990 French Open.
Paz unexpectedly defeated defending champion Arantxa Sánchez Vicario in the second round of the 1990 French Open. Later that year, at the Virginia Slims of Worcester, Paz also defeated Sánchez Vicario in the round of 16. Five years before, in the semifinals of the 1985 Brazil Open, she beat top-seeded Gabriela Sabatini en route to beating Peruvian Laura Arraya for the title. In so doing, Paz became the first Argentinian woman to capture a major WTA event. In addition to wins over Sánchez Vicario and Sabatini, she also defeated top-seeded Jana Novotná in three sets to reach the semifinals of the Belgian Ladies Open in Brussels in 1989. The previous year, at the 1988 Hilton Head tournament, Paz had defeated Novotná in the round of 32 for the first time.