The 1990–91 UEFA Cup was the 20th season of the UEFA Cup, the secondary club football competition organised by the Union of European Football Associations (UEFA).

The final was played over two legs at San Siro, Milan, Italy, and at the Stadio Olimpico, Rome, Italy.

The competition was won by Internazionale, who defeated fellow Italian team Roma by an aggregate result of 2–1 to claim their first UEFA Cup title.

For the second consecutive year, two Italian teams reached the final of the UEFA Cup, This was the first European title for Internazionale in 26 years, after their two consecutive European Cup triumphs in 1964 and 1965.

This tournament also marked the return of English clubs, after a five-year ban resulting from the Heysel Stadium disaster in 1985.

A total of 64 teams from 32 UEFA member associations participated in the 1990–91 UEFA Cup, all entering from the first round over six knock-out rounds.

The association ranking based on the UEFA country coefficients is used to determine the number of participating teams for each association: For the 1990–91 UEFA Cup, the associations are allocated places according to their 1989 UEFA country coefficients, which takes into account their performance in European competitions from 1984–85 to 1988–89.

Having returned to European competitions after serving its five-year ban, England's score was limited to the first of the five seasons accounted for in the ranking, and only one English club competed in the UEFA Cup, from a previous total of four.

Borussia Dortmund won 4–0 on aggregate.

3–3 on aggregate; Real Sociedad won on away goals.

Admira Wacker won 4–0 on aggregate.

FC Magdeburg won 1–0 on aggregate.

Aston Villa won 5–2 on aggregate.

Chornomorets Odesa won 4–3 on aggregate.