He was born on June 8, 1920 in Paraisópolis, Minas Gerais, son of Judge Amilcar Augusto de Castro and Maria Nazareth Pereira de Castro. His father’s profession required a lot of moving around, which caused the family to live in several cities, until they settled in Belo Horizonte, in 1935.
In 1941, he entered the Law School of the Federal University of Minas Gerais, earning his Bachelor degree in 1945.
In 1944, he enrolled in the School of Architecture and Fine Arts, attending the course of drawing and painting given by Alberto da Veiga Guignard. The courses were unified at the creation of the Institute of Fine Arts. Amilcar was part of the first group, becoming closer to Guignard.
In 1945, he was selected for the 51st National Exhibition of Fine Arts.
In 1947, he received a Bronze Medal at the V Hall of Modern Art of the Ministry of Education and Culture (MEC), in Rio de Janeiro. The works selected were two drawings of Ouro Preto. It was the first official recognition of his artistic career.
In 1950, he was part of the 55th National Exhibition of Fine Arts, with works Nu and Mascara de Ceschiatti. (Nude and Mask of Ceschiatti)
In 1951, he received a bronze medal (Sculpture category) at the III Salão Baiano de Belas Artes, in Salvador. In the same year he was part of the modern division of the 56th National Exhibition of Fine Arts with a sculpture and two drawings.
In 1955,won the 1st place in the Sculpture Prize at the National Exhibition of Modern Art of Bahia.
In 1956, he joined the National Exhibition of Concrete Art, organized by Grupo Ruptura.
In 1956/57 the exhibition was presented in São Paulo (MAM-SP) and Rio de Janeiro (MAM-RJ).
On March 23, 1959, he signed the Neoconcrete Manifesto - published in the Sunday Supplement of Jornal do Brasil -, written by Ferreira Gullar and also signed by Lygia Pape, Reynaldo Jardim, Franz Weissmann and Theon Spanudis..
Between 1959 and 1961 the neoconcrete group organized three exhibitions: - 1959 - MAM-RJ (Rio de Janeiro) and Belvedere da Sé (Salvador) - 1960 - MEC (Rio de Janeiro) - 1961 - MAM-SP.
In 1960, he participated in the international exhibition of concrete art "Konkrete Kunst", organized by Max Bill in Zurich. In 1963 he made the stage set for the Samba School Estação Primeira de Mangueira, aided by friends and artists Jackson Ribeiro and Hélio Oiticica.
In 1965 he won the Guggenheim Foundation Prize, awarded for the years 1968 to 1969. It was the first time that a Brazilian artist received the grant from the Guggenheim Foundation.
In 1967, he won the Foreign Travel Prize of the XVII National Exhibition of Modern Art (MEC, Rio de Janeiro).
In 1968 he moved to the United States.
In 1969 he made an individual exhibit at the Kornblee Gallery (New York).
He made other exhibits at Convent of the Sacred Heart and New York University, both in New York.
He won the Guggenheim Foundation scholarship once again.
He returned to Brazil and decided to live in Belo Horizonte.
He began his career as a professor, giving classes in sculpture and arts at the Ouro Preto Arts Foundation, and at the Guignard School, where he became director. During the 70's and 80's he taught sculpture, drawing, form theory and composition at the School of Fine Arts of the Federal University of Minas Gerais. He retired as a teacher in 1990.
In 1973 he resumed drawing works that were formerly sculpture projects and now are independent works. These works were unknown to the public until 1976, when they were exhibited at the IV Global Winter Show in 1976 in Belo Horizonte.
In 1975, he developed acrylic paintings with brushes and brooms.
In 1977, he received in the category Drawing, the prize of the Panorama of Brazilian Art, organized by MAM-SP.
In 1978 he was awarded in the Sculpture category.
In 1978, he made his first solo exhibit in the country, showing drawings in the Raquel Arnaud Art Office (São Paulo). In the 80's and 90's he made several exhibitions in the gallery.
Also in 1978 it executed his biggest sculpture of 32m for the city of Ouro Branco, MG.
In 1979, he participated in the special room of the XV International Biennial of São Paulo.
In 1984, he participated in the project of the School of Arts and Crafts of Count - EAOC, MG. Project aimed at underprivileged students, which was not taken forward by the government authorities.
In 1989, with the curatorship of Paulo Sergio Duarte, his first retrospective was held, in the Imperial Palace of Rio de Janeiro.
In 1992, in São Paulo, MASP holds a new retrospective.
He made several exhibits in the 90's and participated in collectives in Brazil and abroad.
In 1995, he received the National Award from Funarte - National Art Foundation - and the Ministry of Culture.
In 1997, he was awarded the first edition of the Johnnie Walker Plastic Arts Prize.
In 2001, he inaugurated his new studio in Nova Lima, MG, with the project of the architect Allen Roscoe.
He died in Belo Horizonte, on November 22, 2002.