Sylvio de Vasconcellos, 62, a retired official of the Organization of American States who had lived in Washington since 1972, died of respiratory failure Wednesday at George Washington University Hospital.

He had worked as an urban development specialist for the OAS for two years, first in Mexico City and then in Washington, before retiring in 1973. Since then he had worked as a consultant to the Costa Rican government, the OAS, and the Smithsonian Institution.

The author of a number of works on Brazilian history and architecture, he also contributed articles to publications in this country and Latin America.

Dr. Vasconcellos was a native of Brazil. He earned a doctoral degree at the Federal University of minas Gerais in Brazil, where he began a 20-year career as a professor of architectural history in 1948.

He also helped direct conservation of government art and buildings and restoration projects in Brazil for 30 years before becoming a Guggenheim fellow in 1970.

Survivors include his wife, Muriel, of the homes in Washington and Brazil; three daughters, Andrea, Claudia and Sylvia; five brothers and sisters, of Brazil, and five grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Brazilian-American Cultural Institute