The Brazilian Democratic Movement (Portuguese: Movimento Democrático Brasileiro, MDB) was a political party in Brazil that existed from 1965 to 1979. It was formed in 1965, when the military government that overthrew President João Goulart abolished all existing political parties. The new electoral rules were so restrictive as to permit the existence of only two parties—the National Renewal Alliance Party (ARENA) and the MDB.
The MDB became the official party of the opposition, bringing in members from many of the former political parties. The bulk of its membership came from the former Brazilian Labour Party and the left wing of the Social Democratic Party. The MDB lacked a unified political position, being an umbrella organisation that harboured centrists, liberals, leftists, and conservatives who opposed the military regime.
At first, the MDB did not have real power in Congress, and as such boycotted the indirect presidential elections. However, in the elections of 1974 it took almost enough seats to gain a majority. As a result, the military government passed legislation restricting the power of the opposition, and even annulled the election of certain MDB Congressmen.
The MDB participated in the indirect presidential elections of 1974 and 1978 with two "anti-candidates", Ulysses Guimarães and General Euler Bentes Monteiro. The MDB used these campaigns to gain the attention of the global media, and denounce the "democratic" facade of the Brazilian dictatorship.
In 1979, in what may have been an attempt to split-up the opposition—or, on the other hand, a concession to reality—the military government allowed the formation of new parties, and the majority of the MDB became the Party of the Brazilian Democratic Movement (PMDB).