In Croatia, the Opposition (Croatian: Oporba) comprises all political parties represented in the Croatian Parliament that are not part of the Government which is supported by the parliamentary majority.

The Leader of the Opposition (Croatian: Šef oporbe) is an unofficial, seldom used title held by the leader of the largest party with no representatives within the government. Where one party wins outright this is usually the leader of the second largest political party in the Parliament (usually the Croatian Democratic Union (HDZ) or the Social Democratic Party (SDP)).

The current Leader of the Opposition is Siniša Hajdaš Dončić, president of the SDP, who took up the role on 21 September 2024, after winning the elections for the head of the Social Democratic Party.

Ivica Račan of the Party of Democratic Changes led the opposition in 1990 and 1991.

The Cabinet of Franjo Gregurić formed in 1991 was a National Unity Government.

Dražen Budiša of the Croatian Social Liberal Party led the opposition between 1992 and 2000.^{[citation needed]}

Vladimir Šeks led the Croatian Democratic Union in opposition until the election of Ivo Sanader in 2000.

Ivica Račan led the opposition between 2003 and 2007. Željka Antunović became the head of SDP after his death, until Zoran Milanović was elected.