Parker T. Hart, 87, an author, linguist and authority on the Middle East who served as an assistant secretary of state and ambassador to three countries, died Oct. 15 at his home in Washington. He had a heart ailment.

He served in the State Department's Foreign Service for 31 years, attaining the rank of career minister and the reputation of a consummate professional before retiring in 1969. Over the years, he served as ambassador to Saudi Arabia, Turkey and Kuwait and as minister to Syria and Yemen.

Mr. Hart was assistant secretary of state for Near East and South Asian affairs from 1968 to February 1969, when he was named director of the Foreign Service Institute. He retired later that year.

After leaving the government, he spent two years as president of the prestigious Middle East Institute in Washington. He was a consultant with Bechtel Corp. from 1972 to 1990.

Mr. Hart held high and important posts dealing with the Middle East during an era of tumultuous and momentous events. He was counselor of the U.S. Embassy in Cairo during the 1956 Suez War and was minister in Syria two years later when governments were overthrown in Syria and Iraq and U.S. Marines landed in Lebanon. After serving as deputy assistant secretary of state for the Near East from 1959 to 1961, he began a four-year tour as ambassador to Saudi Arabia.

In 1975, in a letter to The Post on the death of King Faisal, Mr. Hart pointed out that he had known the late Saudi king and Saudi Arabia itself for 30 years. A great admirer of Faisal, he wrote of having seen the country develop under the king's leadership into an enormous economic power from a "newly united collection of illiterate tribes deprived of almost all the resources needed to cope with modern statehood."

While serving as ambassador to Saudi Arabia, he also served for a time as minister to Yemen and ambassador to Kuwait. While in Arabia, he explored some of its more remote areas, places where few, if any, westerners had ventured.

As ambassador to Turkey from 1965 to 1968, he was a leading participant in successful efforts to prevent war between Greece and Turkey, both NATO members and U.S. allies, over sectarian strife on the island of Cyprus. While ambassador, he learned the Turkish language and managed to visit 63 of the nation's 67 provinces.

After becoming director of the Foreign Service Institute, the State Department's chief training facility, it was announced that he had set a language-proficiency record, having passed more language tests than any other senior Foreign Service officer. He was fluent in Arabic, Turkish, French, German and Portuguese and spoke English with what one reporter called a "Boston Brahmin" accent. The reporter also said that Mr. Hart was a diplomat of the old school, "well-mannered and courteous to a fault."

Parker Thompson Hart was born in Medford, Mass., and was a 1933 graduate of Dartmouth College. He also received a master's degree in diplomatic history from Harvard University and a diploma from L'Institut des Hautes Etudes Internationales in Geneva. He also studied at Georgetown University's foreign service school and was a 1952 graduate of the National War College.

He joined the State Department in 1937 as a French translator and became a Foreign Service officer in 1938. His first foreign posting took him to Vienna, where he witnessed the Nazi Anschluss, or annexation of Austria to the German Reich. While there, he helped Jews fleeing to the United States and Palestine. During World War II, he served in Brazil, where his duties included investigation of possible Nazi operations.

In 1944, his career took its turn toward the Middle East when he opened the first U.S. consulate in Saudi Arabia, at Dhahran. He was consul general in Dhahran from 1949 to 1951, then in 1952 was named director of State's office of Near Eastern Affairs.

Mr. Hart was the author of a book on the 1967 Cypriot crisis, "Two NATO Allies at the Threshold of War," published by Duke University Press in 1990. In the next year, Indiana University Press is to publish his second book, "Saudi Arabia and the United States: Building a Security Partnership."

Survivors include his wife of 48 years, the former Jane Constance Smiley, of Washington; two daughters, Margaret Hart Espey of Lafayette, Calif., and Judith Hart Halsema of Karachi, Pakistan; and four grandchildren. LLOYD M. VAN LUNEN Sr. Navy Captain

Lloyd M. Van Lunen Sr., 71, a retired Navy captain who commanded submarines and later worked as consultant to defense contractors, died of lung cancer Oct. 15 at his home in Davidsonville.

Capt. Van Lunen, who was born in Grand Rapids, Mich., graduated from Dartmouth College and received a master's degree in history from Boston University.

He began his 28-year naval service in 1942. During his career, he commanded the submarine Sea Leopard and the submarine service ship Gilmore. He retired to Davidsonville in 1970.

Survivors include his wife of 52 years, Judith Bailey Van Lunen of Davidsonville; three children, Lloyd Jr., of Brunswick, Maine, and Elizabeth A. Van Lunen and Mark Van Lunen, both of Davidsonville; and a sister.