Frederick Wilkerson, 67, a noted voice teacher and coach in Washington and New York whose pupils included Roberta Flack and other stars, was found dead Saturday in his apartment in New York City. He lived on S Street NW in Washington.

A New York City medical examiner said Mr. Wilkerson died of strangulation and multiple rib fractures and that the case has been ruled a homicide. A New York police official said last night that no arrests had been made.

Mr. Wilkerson had been singing for most of his life and had been teaching and coaching for about 35 years. He also was head of the Wilkerson Scholarship Choir, which has appeared in the Kennedy Center with Flack conducting.

Besides Flack, Mr. Wilkerson's pupils included Kenneth Riegel, William Parker, Alberta Driver, John Waddell, Mary Beck, Joyce Bryant, Earl Hyman, Steven Janzen, and Inez Matthews. He also coached Paul Robeson at one point and gave some advice to Marian Anderson.

He also gave lessons to Phyllis Diller to help her project her speaking voice.

Mr. Wilkinson himself sang under the stage name of Gilbert Adams. In 1947 he worked in a production of "Porgy and Bess," starring Leontyne Price and William Warfield.

"Your body is 89 percent water, something like that," he once told an interviewer, "and so are your bones, so you must think of your whole body as a sounding box. You must feel every syllable you say all the way down to your feet, all the way to your toes.

"I tell my pupils to start practicing early in the day. You should start your voice early and keep it up all day, working while you talk. You're singing all the time."

Mr. Wilkerson began singing in Temple, Tex. where he was born and where he was known as "that boy with the tenor voice." When he was 13, he joined the Williams Quintet, an offshoot of the pioneering Williams Jubilee Singers. The group came through Temple minus a tenor and that gave Mr. Wilkerson his chance. He later became a baritone.

He trained at Brick's College in North Carolina, sang in various choirs, and studied with Elizabeth Loguen, a voice teacher who had been an assoicate of William Thorner, one of the great voice coaches of the Caruso era. He decided on a career as a teacher and coach about 1947.

For about five years in the late 1940s and early 1950s, he taught at Howard University. Then he moved to California for six years. He returned to Washington in 1960 and this became his permanent home base. He had rented the apartment in New York for about three years.

Mr. Wilkerson's survivors include a brother, Robert, of Temple.

Friends suggests that expressions of sympathy be in the form of contributions to the Frederick Wilkerson Scholarship Foundation, 1207 Floral St. NW.