Sergio and Estíbaliz were a Spanish vocal duo, formed by Sergio Blanco Rivas and Estíbaliz Uranga Amézaga who also worked with groups Mocedades and El Consorcio. They were also known for their participation in the Eurovision Song Contest 1975. Both were born in Bilbao.
Having met in 1968, the couple joined vocal group Mocedades, with whom they recorded three albums before leaving in 1972 to concentrate on a career as a duo. They released their first self-titled album the following year, which proved a success and was followed by further albums at approximately yearly intervals throughout the 1970s.
In 1975 Sergio and Estíbaliz were chosen internally by broadcaster Televisión Española as the Spanish representatives for that year's Eurovision Song Contest with the song "Tú volverás". At the 20th Eurovision Song Contest, held in Stockholm on 22 March, "Tú volverás" placed 10th of the 19 entries. The song became a major hit both in Spain and Latin America, where they became very popular, leading to the release of an album of Latin American songs in 1977.
The couple had married in 1975, and took a career break in the early 1980s during which Estíbaliz gave birth to a daughter.