Dr. Winston Churchill Willoughby, 70, a Washington dentist and civic leader who also became known as an ambassador without portfolio, died of fungus infection Saturday at Howard University Hospital.

In 1975, he was named Dentist of the year by the D.C. Dental Society, of which he was a member. He continued to pratice here until becoming ill last fall.

Dr. Willoughby was born in Port of Spain, Trinidad. He came to this country in 1920, and lived for a short period in New York before moving to Washington. He earned a degree in dentistry from Howard University in 1933. He became an American citizen three years later.

From 1938 to 1944, he was staff director of the D.C. Health Department's school clinic.He then resigned to devote full time to private practice.

In World War II, Dr. Willoughby served in an advisory capacity with the Office of Price Administration and recieved Certificate of Appreciation from Presidents Roosevelt and Truman.

Widely traveled, he was a friend of many high-ranking diplomats here and of member of Congress. He helped numerous needy students who came to Howard University from Trinidad.

In 1967, Dr. Willoughby was honored by both the House Committee on Foreign Affairs and the House Judiciary Committee. He received the United Nations Humanitarian Award in 1972.

He was a fellow of the International College of Dentistry, a member of the American Dental Association. He had been active in the Boy Scouts and was a member of the Board of governors of the National Graduate University here.

A founding member of the northwest Kiwanis Foundation, he was a member of the board of directors of Kiwanis International and of station WETA-TV.

Dr. Willoughby wrote poetry and music. A poem, "Keep Me in Your Heart," was published and set to music.

He is survived by his wife, Anselee (Ann), and two daughters, Michelle and Gina, all of the home in Washington, and two brothers, Aubrey and Roland, both of New York City.