Domínguez competed early in her career at 1,500, 5,000 and 10,000 metres. She competed as a 20-year old in the 1996 Summer Olympics, finishing 9th in her initial heat in the 1,500m event. In 1998 Domínguez won her first championship medal in the European Championships in Budapest in the 5,000m, winning bronze behind Sonia O'Sullivan, who won gold and Gabriela Szabo, who took silver. In 2002, she won these events at the European indoor and outdoor championships, and won her second straight title in 2006 in the 5,000 metres at the European outdoor championship (also obtaining the Championship Record). She also has silver medals from the World Championships in 2001 and 2003, and she was named Spanish Athlete of the Year in both years.