The Rev. Elman J. Folkenberg, 66, a former official with the Seventh-Day Adventist Church who helped develop a widely respected five-day plan to help smokers kick the habit, died of cardiac arrest Jan. 19 at Montgomery General Hospital. He lived in Dayton, Md.

"Although he didn't smoke, Mr. Folkenberg was frequently approached by people in his church who wanted to know what they could do to stop smoking," said Ernest H.S. Steed, an assistant to the president of the Seventh-Day Adventist Church and the director of the Five-Day Plan from 1968 to 1981. Smoking is against the doctrine of the Seventh-Day Adventist Church.

Steed said Mr. Folkenberg began looking for a remedy to the smoking problem during the 1940s and early 1950s, when he was the pastor of several Seventh-Day Adventist churches in central California. He took the problem with him to London, where he went in 1955 as the director of the Seventh-Day Adventist Church center, and he found an answer in South Lancaster, Mass., where he worked when he returned to this country in 1958.

It was in South Lancaster that he and Dr. J. Wayne McFarland, an Adventist physician, developed the Five-Day Plan to Stop Smoking. It began in 1960 and it includes five days of group therapy sessions, a "buddy system" and further personal contact. Since then, it has been established in more than 90 countries.

Although no one claims the Five-Day Plan is the whole answer, it has had some notable successes. Seventh-Day Adventist officials say about 50 percent of the people who start the program are still free of tobacco three years later. Steed says it has worked for more than 15 million people.

A spokesman for the American Heart Association described the program as successful. A spokesman for the American Cancer Society said the society has recommended it as an alternative to its own smoke-ending program.

Despite the success of their work, the names of Folkenberg and McFarland are not generally connected with it.

For five years after the plan began in South Lancaster, Mr. Folkenberg was its director. In 1965, he moved to Seventh-Day Adventist headquarters in Takoma Park. For the next six years, he was the head of Narcotic Education Inc., a church organization. Since 1971, he had been a consultant on health problems and smoking cessation in this country and in Sweden, Norway and Canada.

Mr. Folkenberg was born in San Diego and graduated from Pacific Union College. He began his career as a pastor after finishing college.

Survivors include his wife, Gloria, of Dayton; two children, Judy Folkenberg of Bethesda and Michael Folkenberg of Laurel; one brother, Stanley, of Spokane, Wash., and one grandson.