Members of the National Organization for Women will hold overnight vigils this weekend at 18 clinics nationwide -- two in the Washington area -- to protect the clinics from the possibility of new violence on the eve of the presidential inauguration and the 12th anniversary of the U.S. Supreme Court decision legalizing abortions, the group said yesterday.

"The antiabortion terrorists who have bombed or burned nearly 30 abortion clinics during the past year are determined to take the law into their own hands and end safe, legal abortion," said NOW President Judy Goldsmith. "We are even more determined to stop them."

NOW's vigil does not have the support of several of its usual allies on the abortion issue, such as the Planned Parenthood Federation of America and the National Abortion Federation. "If the only way to avoid increasing the risk is to do nothing, that is unacceptable," said Goldsmith, reacting to fears of other prochoice groups that the overnight vigils may provoke attacks.

Agents from the federal Bureau of Alcohol, Tobacco and Firearms also have questioned the wisdom of the vigils, but Goldsmith said that the bureau did not ask NOW to call off the vigils.

To protect its clinic occupants, NOW has instructed its members to keep lights burning, post signs about the vigils and alert the press and police.

Goldsmith will spend tonight in the Women's Medical Center, a clinic in a District office building in the 1700 block of I Street NW. The other local vigil will be held at the Commonwealth Women's Clinic in Falls Church.

Staff members of various clinics spoke at NOW headquarters, denouncing the violence and tactics of some antiabortion pickets. "It makes me angry when I read that nobody has been hurt by this bombings ," said Penny Smith, administrator of Metro Medical and Women's Center in Wheaton, which was bombed Nov. 19. "Our patients have been hurt" by delays in services and fear, she said. Smith said that the clinic will reopen next month in Montgomery County.

Goldsmith sent telegrams yesterday to the leaders of three antiabortion groups, urging them not to compare abortion to "the holocaust, slavery and murder." Such language, she said, "is not only inflammatory, it is repugnant as an attempt to justify terrorism."

Goldsmith called on the FBI to end what she termed "illegal" harassment of clinic patients. " [Pickets] carry dismembered dolls covered with red paint and signs with hunks of raw meat on them," she said. "This, and calling patients at home to threaten them, is not a legitimate exercise of free speech."

Judy Waxman, director of the board of the District clinic, said that D.C. police have promised to station a squad car outside the clinic at night during the vigil. "We are more secure now that we have women protecting other women and protecting our right to choose," she said.