The United Democratic Party (UDP) is an opposition liberal party in Tanzania. The party is an observer at Liberal International.
At the 2000 legislative elections, the party 2 out of 269 seats in the National Assembly. In the presidential elections of the same day, its candidate John Cheyo won 4.2% of the vote.
The party didn't field a presidential candidate in the 14 December 2005 election, but did win one seat in National Assembly elections held on the same day.