Myrtle D. Mix, 89, a retired registered nurse who spent the early days of her career serving in remote mining camps in New Mexico, died Sunday at Sibley Memorial Hospital following a stroke.

Mrs. Mix was born in the Thousand Islands region in New York. She took her nurse's training in Philadelphia and then went to Raton, N.M., as part of a special medical team assigned to mining camps in the mountains. Much of her work required travel by horseback.

Mrs. Mix later lived and worked in Denver, and Phoenix, Ariz. Among her jobs was teaching home nursing and hygiene in Arizona Indian schools. During World War II. she taught home nursing for the American Red Cross.

While in New Mexico, Mrs. Mix married Dr. Harry M. Smith. He died in 1920. She later married Dr. Walter S. Mix, who died in 1933.

Mrs. Mix moved to the Washington area in 1972 and lived with a daughter, Mrs. John M. Dower, in Chevy Chase.

In addition to Mrs. Dower, survivors include five sisters, Florence Russell, of Binghampton, N.Y., Lillian Kittle, Mildred Cummings and Marjorie Rusho, all of Clayton, N.Y., and Caroline Archambault, of Rochester, N.Y.; two brothers, Rawdon Dano, of Clayton, N.Y., and Melzer Dano, of St. Lawrence, N.Y., and five grandsons.

The family suggests that expressions of sympathy be in the form of contributions to All Saints Church, Chevy Chase, Md.