"Si Tú Supieras" ("If You Knew") is a song written by Kike Santander and performed by Mexican recording artist Alejandro Fernández.

It was co-produced by Santander and Emilio Estefan and was released as the first single from Me Estoy Enamorando by Sony Music Mexico on 18 August 1997.

It reached the top of the Billboard Hot Latin Songs chart in the United States and spent a total of six weeks at this position.

"Si Tú Supieras" has been covered by other artists including Tony Vega, Manuel Mijares, Noel Schajris, and Chamin Correa.

"If I had released another album of just rancheras, people would have just expected the same thing, and then they would have begun to judge me by that one [musical] theme", Fernández explained.

[14] It later reached number one again on the week of 3 January 1998 and was succeeded by Fernández and Gloria Estefan's song "En El Jardín".

[4] Eliseo Cardona of El Nuevo Herald highlighted "Si Tú Supieras" as one of the boleros where Fernández performs with "intensity and passion".

[24] In 1998, Puerto Rican salsa singer Tony Vega covered "Si Tú Supieras" on his album Hoy Quiero Cantarte.

AllMusic editor Jon O'Brien criticized Schajris for choosing to "play it safe with perfunctory covers of drippy romantic ballads" with "Si Tú Supieras" being cited as one of the examples.

[29] Mexican guitarist Chamin Correa performed an instrumental version on his album Cuerdas Amor Y Guitarra, Vol.