United Macedonian Organisation: Ilinden–Pirin (Обединена македонска организация: Илинден–Пирин) is an Macedonian organisation in Bulgaria, whose self-declared aims are protection of the human rights, language and nationality of the Macedonian minority in the country. In Bulgaria itself the organization is regarded as a foreign government-funded separatist organization.
In 1999, the organisation was registered as a political party and took part in the municipal elections the same year. The party polled approximately 3,000 votes in the party's core region, Blagoevgrad Province (Pirin Macedonia), in line with the number of self-declared ethnic Macedonians in the region according to the latest Bulgarian census (3,100 in 2001). The party received, however, almost no votes in the rest of the country.
On February 29, 2000, by decision of the Bulgarian Constitutional Court, UMO Ilinden–Pirin was expelled from the Bulgarian political system, as a separatist party. On November 25, the European Court of Human Rights in Strasbourg, condemned Bulgaria because of violations of the OMO Ilinden–Pirin's freedom of organising meetings. The court stated that Bulgaria had violated Act 11 from the European Convention of Human Rights.
On 26 June 2006, the party held a new founding meeting and provoked some controversy in the Bulgarian media. The meeting was held in the southwestern town of Gotse Delchev despite an IMRO-BNM protest demonstration. IMRO-BNM deputy Boris Yachev accused the Macedonian government of sponsoring the party with €75,000 and called for the recall of the Macedonian ambassador Abdurahman Aliti. The party's leader, Stojko Stojkov, called the party Bulgarian and not ethnically based.