The International Democrat Union is an international grouping of conservative and Christian democratic parties. Headquartered in London, its members include:
- Kuomintang (Republic of China on Taiwan)
- Liberal Party of Australia
- Conservative and Unionist Party (United Kingdom)
- Hannara (Grand National Party, Republic of Korea)
- Progressive Conservative Party of Canada
- New Zealand National Party
- CDU/CSU (Germany)
- New National Party (South Africa)
- Republican Party (United States)
The current chairman is Prime Minister of Australia John Howard.
The IDU has a number of regional organisations, as well as the International Young Democrat Union and International Women's Democrat Union.