Fudbalski klub Željezničar is a professional football club, based in Sarajevo, Bosnia and Herzegovina. The name Željezničar means "railway worker", from its being established by a group of railway workers. In Bosnia, the club is traditionally known for producing talented players, rather than signing them. The club often sells its most talented players at the end of each season in order to stabilize or increase its finances.
During the time of the former Yugoslavia, FK Željezničar were national champions in the 1971–72 season, qualifying the club for the European Cup during the 1972–73 season where they were eliminated in the first round. The club has also finished as runners-up once in the league, as well as playing in a 1980–81 Yugoslav Cup final. In Europe, the club is most famous for reaching both the UEFA Cup semi-finals during the 1984–85 season and the quarter-finals during the 1971–72 season.
The club is the first Bosnian team to reach the UEFA Champions League finals and one of the few teams ever to do so from Yugoslavia. Željezničar is the most successful football team in present-day Bosnia.