Spîrlea became a professional tennis player in 1990 and for many experts - like her compatriot Ion Tiriac - was one of the greatest young talents in the world.
Spîrlea secured her first title on the WTA Tour in 1994 in Palermo. In the same year she was nominated for the Newcomer of the Year award. In 1995 she defended her title at the clay court tournament in Sicily. She celebrated her greatest triumph in 1996 with a final victory over Mary Pierce at the traditional tournament in Amelia Island . She won her fourth and final title in Strasbourg in 1998. Irina Spîrlea was one of the top ten in the world rankings and was listed at number 7 in October 1997.
Between 1991 and 1994 she played 18 games in the Fed Cup for Romania , of which she won ten.
Her greatest sporting success was her participation in the semi-finals at the 1997 US Open . After defeating Monica Seles, she lost to Venus Williams . Spîrlea missed two match points and lost 6: 7, 6: 4 and 6: 7. During the game there was an argument between the two players, which even resulted in a bump when switching sides. She had already made negative headlines at the tournament in Palermo when she was the first woman in tennis to be disqualified for insulting a referee. In the same year Spîrlea moved into the quarter-finals at the Australian Open and was in the second round at the French Open and Wimbledon.
In 1998 she defeated the top ten players Lindsay Davenport and Monica Seles en route to the Hilton Head Islands final . At the US Open , she defeated Serena Williams 6: 3, 0: 6, 7: 5 in the third round and qualified as in the previous year for the Women's Masters, in which she reached the semifinals again. In 1999, however, it fell far behind.
In addition, the right-hander won six double titles in her career.
After many injuries, Spîrlea ended her ten-year professional career in 2000. In 2001 she married her Italian trainer Massimiliano Pace and became a mother in 2002.