Portugal was represented at the Eurovision Song Contest 1985 with the song "Penso em ti, eu sei", composed by Tozé Brito, with lyrics by Adelaide Ferreira and Luís Fernando, and performed by Ferreira herself.

Radiotelevisão Portuguesa (RTP) held the Festival RTP da Canção 1985 at the Coliseu dos Recreios in Lisbon on 7 March 1985, hosted by Margarida Andrade and Eládio Clímaco.

The winning entry was "Penso em ti, eu sei", composed by Tozé Brito, with lyrics by Adelaide Ferreira and Luís Fernando, and performed by Ferreira herself.

Adelaide Ferreira was the ninth performer on the night of the contest, following Belgium and preceding Germany.

At the close of the voting the song had received 9 points, placing 18th in a field of 19 competing countries.