Portugal was represented at the Eurovision Song Contest 1964 with the song "", composed by João Nobre, with lyrics by Francisco Nicholson and Rogério Bracinha, and performed by António Calvário. The Portuguese participating broadcaster, (RTP), selected its entry for the contest at the 1964. This was the first-ever entry from Portugal in the Eurovision Song Contest, and the first-ever entry performed in Portuguese in the contest.
(RTP) held the 1964 on 2 February 1964 at 22:25 UTC in its Lumiar studios in Lisbon, hosted by Maria Helena Fialho Gouveia and Henrique Mendes. Twelve songs took part in the final and each artist sung two songs. Armando Tavares Belo conducted all the songs. The winning song was chosen by a distrital jury, composed by three members, each had 5 votes to be distributed among the songs it intended to award, making a total of 15 votes per district.
The contest was broadcast on RTP.
On the night of the final Calvário performed 11th in the running order, following the and preceding . Only an audio recording of Calvário's performance is known to exist. Voting was by each national jury awarding 5-3-1 to their top 3 songs, and at the close "Oração" was one of four songs (along with the entries from , , and ) which had failed to pick up a single point. This was the third consecutive contest in which four countries had failed to score, and a first time a country debuts with nul-points. The Portuguese jury awarded its 5 points to Italy.
The orchestra during the Portuguese entry was conducted by Kai Mortensen.
RTP assembled a jury panel with ten members, with each member giving votes to their favorite song. The following members comprised the Portuguese jury.
Portugal did not receive any points at the 1964 Eurovision Song Contest.