Dr. Milton McKendree Boyer, 71, a general practitioner of medicine in Damascus, Md., for many years, died Thursday at Montgomery General Hospital after undergoing surgery.

He had entered private practice in Damascus in 1935 with his father, Dr. George M. Boyer, a well known Maryland physician. His father died in 1956.

Dr. McKendree Boyer was on the medical staffs of Sibley Memorial, Frederick Memorial, Suburban and Montgomery General hospitals until his death. He was a former chief of staff and chief of medicine at Montgomery General.

Last spring he was honored by the hospital's medical staff and board of directors as an "outstanding practitioner of medicine, community leader and humanitarian."

Dr. Boyer was born in Damascus. He was a graduate of George Washington University and its medical school. After serving his internship and residency at St. Luke's Hospital in Cleveland, he studied in Vienna, Austria and London.

He was a former president of the Montgomery County Medical Society and of the Medical and Chirurgical Faculty of the State of Maryland (state medical society).

Dr. Boyer belonged to the Southern Medical Association and the American Medical Association, serving as a Maryland alternate delegate to the latter since 1966.

In 1975, he was one of five Maryland physicians appointed to the board of directors of the Medical Mutual Liability Insurance Society of Maryland.

He was a vice president and director of the Bank of Damascus and a charter member of the Rockville and Damascus Lions clubs. He had served on the board of stewards of the Damascus Methodist Church.

He is survived by his wife, the former Helen W.Souder, and a son, McKendree W., both of the home in Damascus; another son, George M. II, and a daughter, Sally Ann, both attending school in Baltimore; a sister, Susan E. Boyer, and a brother, George W., both of Damascus, and another sister, Mary B. Cramer, of Hagerstown, Md.