The greatest success for Kuusysi in Europe took place in the 1985–86 European Cup. This was the second time in the prime European club competition. In the first round the club faced FK Sarajevo, winning 2–1 both home and away, and thus 4–2 on aggregate. In the next round they faced FC Zenit of Leningrad. They took an early lead, but were not able to keep the opponents at bay, and lost 2–1. At home, however, they won 3–1, and thus 4–3 on aggregate and made the last eight, i.e. the quarterfinals. In the draw for the last eight, they were sent against Steaua București. This was a disappointment for the team, as Steaua was virtually unknown in Finland, and they could have faced some much more famous teams. The first leg in Bucharest ended in a goalless draw. Steaua was the dominant team, but goalkeeper Ismo Korhonen kept the opponents at bay. The club decided to play the second leg at the Helsinki Olympic Stadium, even though there was already snow on the ground. It was played in front of lopulta 32 552 spectators, which was the record amount for any Finnish club. The match went on goalless until the very last minutes, when Steaua's Victor Pițurcă managed to score. Kuusysi had to play without Keijo Kousa, who was injured. Ismo Lius and Markus Törnvall did not play either, because the club had been forced to sell them before these matches. Thanks to this success, the club was able to pay 2 million Finnish marks worth of debts, when the total amount had been 2,3 million.