Donald R. Heath, 87, a foreign service officer for over 40 years before retiring in 1961 and the man who was our first ambassador to Vietnam, died of pneumonia Thursday in a nursing home in Orinda, Calif. He had lived in Berkeley, Calif., since 1975.

Mr. Heath became minister to Viet Nam, Cambodia and Laos in June 1950. In July 1953, he was elevated to ambassador to Viet Nam and Cambodia, and minister to Laos, based in Saigon. He held those posts until September 1954.

During those years in Saigon, he was seen by most observers as a supporter of Vietnamese Emperor Bao Dai and the French presence in Indochina. He called for greater American aid to French military forces, and survived several assassination plots.

Before his Southeast Asian assignment, Mr. Heath was minister to Bulgaria from 1947 until recalled from that post when this country severed diplomatic relations with that country in February 1950.

Relations were broken off after the Bulgarian government accused Mr. Heath of plotting against the Bulgarian government through his connections with Traicho Kostov, a former Bulgarian deputy prime minister, who had recently been hanged for treason.

The State Department also noted in its official communication to Bulgaria that U.S. diplomats found it impossible to function due to travel restrictions, denial of housing and actions taken against Bulgarians associating with our diplomats. Diplomatic relations were not restored until 1959.

After leaving Vietnam, Mr. Heath's served as a delegate to the United Nations, was ambassador to Lebanon from 1955 to 1958, then was ambassador to Saudi Arabia until retiring from the government in 1961.

Mr. Heath was a native of Kansas. He attended Washburn College there and the University of Montpellier in France. He was an infantryman in France during World War I, and a newspaper reporter before joining the State Department in 1920.

He was stationed in Europe and Latin America with the Consular Service, was first secretary of our embassy in Berlin from 1938 to June 1941. In 1944, he became a political adviser to on Gen. Eisenhower's staff, and later served as political affairs director in the U.S. Military Government in Germany, before going to Bulgaria.

His wife, Louise B. Heath, died in August 1981. Mr. Heath's survivors include a daughter, Sue L. Brown of Kensington, Calif.; a son, Donald R. Jr., of El Cerrito, Calif.; seven grandchildren, and one great-grandchild.