John C. Lang, 68, a retired education specialist for the Defense Department's Bureau of Naval Ersonnel and an adjunct professor at George Washington University from 1950 to 1970, died Tuesday at Prince William Hospital in Manassas after a heart attack.

Dr. Lang joined the Bureau of Naval Personnel after World War II. An authority on curriculum and personnel, he helped the governments of Greece and Turkey set up their naval training programs and served as a naval adviser to other countries, including Iran, Denmark, Spain, Portugal and South Vietnam.

After retiring in 1972, he was a management consultant for a number of professional and technological societies, hospitals, universities and corporations throughout the country.

Most recently Dr. Lang was teaching graduate courses for Central Michigan University and Pepperdine College in Los Angeles.

He was born in Delmont, S.D. He earned a bachelor's degree in chemistry and physics from Valley City State College in North Dakota and a master's degree in personnel administration from Northwestern University. He later graduated with a master's degree and a doctorate in administration and supervision from George Washington University. He also did postgraduate work in chemistry at the University of Colorado.

He served with the U.S. Navy in World War II and was a retired lieutenant commander in the reserve.

Survivors include his wife, Geoline (Gay), of the home; three brothers, Emil, of Casselton, N.D., Andrew, of Virginia, Minn., and Arthur, of Grapeland, Tex.; four sisters, Joanne, of Los Angeles, Helen Rauscher of Sutton, Neb., Erna Pirner of Rapid City, S.D., and LaVelle Mellor of Goulds, Fla.