The 1988 King Cup was the 30th season of the knockout competition since its establishment in 1956. Al-Nassr were the defending champions but they were eliminated by eventual champions Al-Ittihad in the semi-finals.

Al-Ittihad won their 6th title after defeating Al-Ettifaq 1–0 in the final. This was the first final to be held in the King Fahd International Stadium. As winners of the tournament, Al-Ittihad qualified for the 1989 Arab Cup Winners' Cup.

Round of 16 Both Al-Ettifaq and Ohod received a bye to the next round. Al-Ettifaq received due to their participation in the 1988 Gulf Club Champions Cup. Ohod received a bye to the lack of teams participating in this round. The matches of the Round of 16 were held on 31 March and 1 April 1988.

Home team Score Away teamAl-Ettifaq Bye Ohod Bye Al-Ahli 3–3 (2–3 pen.)Al-RiyadhAl-Ittihad 1–0 Al-Qadsiah Al-Tai 0–1Al-Nahda Al-Kawkab 0–2Al-Wehda Al-Tuhami 2–2 (3–4 pen.)Al-ShababAl-Nassr 1–0 Al-Hilal

Quarter-finals The matches of the Quarter-finals were held on 7 and 8 April 1988.

Home team Score Away teamAl-Nassr 4–0 Ohod Al-Riyadh 1–3 Al-ShababAl-Ettifaq 1–0 (aet) Al-Wehda Al-Nahda 0–4Al-Ittihad

Semi-finals The four winners of the quarter-finals progressed to the semi-finals. The semi-finals were played on 12 April 1988. All times are local, AST (UTC+3).

Final The final was played between Al-Ittihad and Al-Ettifaq in the King Fahd Stadium in Riyadh. Al-Ittihad were appearing in their 11th final while Al-Ettifaq were making their 6th appearance.

Top goalscorers RankPlayerClubGoals1 Saleh Al-NajraniAl-Riyadh42 Bassem Abu DawoodAl-Ahli2 Majed AbdullahAl-Nassr Salah Al-MuwalladAl-Ittihad Mohamed Al-SuwaiyedAl-Ittihad

References