Registered nurses at Prince William Hospital voted yesterday by an almost two-to-one margin to join a union, marking the first successful attempt to organize health care workers in Northern Virginia.

By a vote of 66 to 34, nurses at the Manassas hospital decided to form Prince William Health Care Professionals, local 724 of the Service Employees International Union.

We're united and determined to do something good," said Wendy Baumler, a registered nurse and a union organizer, last night. "We would like more nurses at the hospital, better educational benefits and higher wages."

Administrators of the 150-bed hospital said they will not challenge the vote, although they will contest six ballots.

Organizers from the Service Employees Union who began organizing at the hospital in January, said they expect other attempts to organize health care workers as a result of yesterday's vote.

Dave Kromer, assistant director of organization for the Service Employees Union, said he expects area hospital administrators in the area will improve their treatment of workers and raise wages to counter the union's efforts.

The new union, will begin bargaining in the next few weeks, after forming a committee and electing representatives, said Baumler. She said it will push strongly for higher wages."When you consider the mental, physical and emotional strain of our jobs, the pay does not measure up to the level of responsibility," she said.

The union's success in Prince William comes five months after the Teamsters union suffered a defeat its campaign to organize workers at the Alexandria Hospital.