| Competition: | Primeira Liga |
| Season: | 2003–04 |
| Dates: | 16 August 2003 – 9 May 2004 |
| Winners: | Porto 20th title |
| Relegated: | Alverca Paços de Ferreira Estrela da Amadora |
| Continentalcup1: | Champions League |
| Continentalcup1 Qualifiers: | Porto Benfica |
| Continentalcup2: | UEFA Cup |
| Continentalcup2 Qualifiers: | Sporting CP Nacional Braga Marítimo |
| League Topscorer: | Benni McCarthy (20 goals) |
| Biggest Home Win: | Gil Vicente 5–1 Estrela da Amadora (23 September 2003) Nacional 5–1 Braga (25 January 2004) |
| Biggest Away Win: | Académica 0–5 Belenenses (21 February 2004) |
| Highest Scoring: | Gil Vicente 4–4 Nacional (7 December 2003) |
| Matches: | 306 |
| Total Goals: | 726 |
| Prevseason: | 2002–03 |
| Nextseason: | 2004–05 |
The 2003–04 Primeira Liga was the 70th edition of top flight of Portuguese football. It started 16 August 2003 with an opening game between Académica de Coimbra and Sporting Clube de Portugal, and ended on 9 May 2004. It was contested by 18 teams. FC Porto were the defending champions and became champions again, winning the Portuguese title in two consecutive seasons.
The first goal of the season was scored by Académica's Filipe Alvim in the opening game against Sporting CP. The first red card of the season was given to Paços de Ferreira's Portuguese midfielder Pedrinha in the 3rd game of the season against Nacional and the first yellow card was given to Sporting's Portuguese midfielder Custódio in the opening game of the season. Porto's Benni McCarthy was the top scorer of the season, scoring 20 goals.
Porto qualified for the 2004–05 UEFA Champions League group stage, along with Benfica, who qualified for the third round. Sporting, Nacional, Braga and Marítimo qualified for the 2004–05 UEFA Cup; in opposite, Alverca, Paços de Ferreira and Estrela da Amadora were relegated to the Segunda Liga.
Varzim, Santa Clara, and Vitória de Setúbal were consigned to the Liga de Honra following their final classification in 2002–03 season.
The other three teams were replaced by Rio Ave, Alverca, Estrela da Amadora from Segunda Liga.
| Team | Outgoing manage | Manner | Date of vacancy | Incoming manager | Date of appointment | |
|---|---|---|---|---|---|---|
| Académica de Coimbra | Artur Jorge | Resigned | 28 August 2003[1] | Vítor Oliveira | 28 August 2003[2] | |
| Vitória de Guimarães |  Augusto Inácio | Sacked | 8 December 2003[3] | Jorge Jesus | 8 December 2003 | |
| Paços de Ferreira | José Gomes | Mutual Consent | 21 October 2003[4] | José Mota | 22 October 2003[5] | |
| Estrela da Amadora | João Alves | Sacked | 3 November 2003[6] | Miguel Quaresma | 3 November 2003[7] | |
| Gil Vicente | Mário Reis | Sacked | 11 November 2003[8] | Luís Campos | 25 November 2003[9] | |
| Belenenses | Manuel José | Resigned | 22 November 2003[10] | Bogićević | 23 November 2003[11] | |
| Belenenses | Bogićević | Sacked | 19 January 2004[12] | Augusto Inácio | 20 January 2004[13] | |
| Académica de Coimbra | Vítor Oliveira | Sacked | 26 January 2004[14] | João Pereira | 27 January 2004 | |
| Boavista | Erwin Sánchez | Sacked | 8 March 2004[15] | Jaime Pacheco | 8 March 2004[16] |
| Rank | Scorer | Club | Goals[17] |
|---|---|---|---|
| 1 | Benni McCarthy | Porto | 20 |
| 2 |  Adriano | Nacional | 19 |
| 3 | Evandro | Rio Ave | 15 |
| Liédson | Sporting | ||
| 5 | Ricardo Sousa | Boavista | 14 |
| 6 | Derlei | Porto | 13 |
| 7 | Simão Sabrosa | Benfica | 12 |
| 8 | Zé Manuel | Paços de Ferreira | 11 |
| Ferreira | Gil Vicente | ||
| Wender | Braga |
| Player | Nationality | For ! | Against | Result | Date | |
|---|---|---|---|---|---|---|
| 4–0 | ||||||
| 4–2 | ||||||
| 4–0 | ||||||
| 3-0 | ||||||
| 3–1 |
| Month | Player of the Month | ||
|---|---|---|---|
| Player | Club | ||
| September[18] | Juninho Petrolina | Beira-Mar | |
| October[19] | Derlei | FC Porto | |
| November[20] | Pedro Barbosa | Sporting CP | |
| December[21] | Evandro | Rio Ave | |
| January[22] | Benni McCarthy | FC Porto | |
| February[23] | Petit | Benfica | |
| March[24] |  Doula | Sporting CP | |
| April[25] | Rossato | Nacional | |
| May[26] | Benni McCarthy | FC Porto | |
