1963 Brazilian constitutional referendum

Following the resignation of Jânio Quadros on 25 August 1961 and the resistance of the Armed Forces and the upper classes to allowing left-wing Vice-President João Goulart to take office, a serious crisis developed, which almost resulted in a civil war. Goulart, who had been on an official visit to the People's Republic of China, was forbidden to return to the country.

Due to Goulart's massive popular support, rather than removing Goulart from office, the National Congress proposed an amendment to the 1946 Constitution, changing the form of government from presidentialism to parliamentarianism, reducing the powers of the President and creating a new post of Prime Minister. The amendment was approved and the military suspended their veto over Goulart, who took office on Independence Day in 1961.

However, the system of government, which had been based on the German model, did not work well, due to the hurry in which the amendment was approved. The ambitions of Goulart and his rivals Juscelino Kubitschek and Carlos Lacerda, both of whom were seeking to become President in the forthcoming 1965 elections, also contributed to the failure of parliamentarianism.

In less than two years, there were three Prime Ministers; Tancredo Neves (1961–1962), Brochado da Rocha (July–September 1962) and Hermes Lima (1962–1963).

Voters were asked "Do you approve the Additional Act that institutes the parliamentary system?" ("Aprova o Ato Adicional que institui o parlamentarismo?").

1963 Brazilian constitutional referendum

Choice	Votes	%
No	9,457,448	82.02
Yes	2,073,082	17.98
Valid votes	11,530,530	93.85
Invalid or blank votes	755,645	6.15
Total votes	12,286,175	100.00
Registered voters and turnout	18,565,277	66.18

Goulart, having achieved full presidential powers, started his Basic Reforms plan (Reformas de Base), which led to a military coup d'état in April 1964.

• A ditadura militar no Brasil, Volume 3 - Jango: Ascenção e queda, p. 72, São Paulo, Caros Amigos Editora, 2007.