Smokers, perhaps the most minor minority group at the National Cancer Institute, have been told to light their pipes, cigars and cigarettes somewhere other than the NCI director's offices on the National Institutes of Health campus in Bethesda.

The smoking ban, covering the three floors NCI occupies in an 11-story building, is one of the strongest and most far-reaching ever issued in the federal work place. Designated smoking areas are more common in other U.S. offices.

In ordering the ban earlier this month, Dr. Vincent T. DeVita Jr., director of the cancer institute, noted that smoking by employes gives a bad impression to visitors to an institute dedicated to the eradication of cancer.

No penalties for violating the order were announced, but federal officials say that agency heads have "broad discretion" to set health and safety rules.

In his notice to the institute's 1,900 workers, DeVita said that "not smoking is the single most effective step that anyone can take to reduce the chance of getting cancer. There is a growing body of evidence that the nonsmoker's risk is increased by what is known as passive smoking, breathing air contaminated by tobacco smoke."

Even so, DeVita said, " . . . visitors to the office of the director smell cigarette smoke in the corridors and see NCI employes smoking. This creates the impression that the leadership of the institute is not truly committed on this issue and to promoting the health of its employes.

"Therefore, I am asking staff to refrain from smoking at their work stations in any offices in the office of the director . . . ."

Employes who "cannot get through the work day without tobacco" Devita said, "can use the public areas of the building to smoke, but not the office corridors. Those who leave their work stations to smoke remain responsible for their normal day's work."

The director also encouraged nicotine addicts to seek professional help, and noted that the institute's counseling service offers smoking cessation clinics.

DeVita said the no-smoking order, while limited to his office, could be expanded to the rest of the building if NCI division directors and other NIH officials follow his lead. An aide at the cancer institute said yesterday that he anticipates that other officials in the building will ban smoking in their offices.

The Cancer Institute director said it is "not our intent to be punitive toward smokers, but to provide a healthful work place for all employes." He said he wanted "to set a positive example for ourselves and the nation, and to demonstrate that we mean what we say about not smoking, while providing support and assistance to those who wish to quit."

Some smokers at the NCI maintain that the order opens the door for similar directives from other parts of the giant health agency.

"What if the director of the National Institute of Dental Research orders employes to have their teeth cleaned once a month?" one asked.

"Suppose the director of the National Eye Institute orders employes to eat carrots every day . . . or what if the Heart, Lung and Blood Institute orders everybody to jog 15 minutes a day?"

Although there is no other mandatory health policy for NIH employes, signs all around the building urge able-bodied staffers to "Walk Down Two Flights or Walk Up Two Flights of Stairs" rather than use elevators.

NIH, incidentally, does have several of the best jogging/racing teams in the Washington area. But officials say there is no plan to make work-related exercise mandatory for any group of workers.