The strike kicked off at about 4 a.m. as many began marching with picket signs outside the Ronald Reagan UCLA Medical Center in Westwood.
UC officials say the strike will cost an estimated $20 million in lost revenue and to cover the cost of replacement workers.
The two-day strike is an effort by their union to reach an agreement after 11 months of negotiations with the hospital over issues concerning understaffing and other problems that may hinder patient care.
"We're out here because we want to be able to provide excellent patient care to the patients that come in," said Demetria Warren, a cardiac surgical technician.
Lynn Leslie says there should be 22 respiratory therapists on her shift, not 17.
"We have a patient ratio," said Leslie. "I can only do five vents at a time. If you have people on life support, adding more work just makes it scarier for the patient."
Tom Rosenthal, chief medical officer at Ronald Reagan UCLA Medical Center, says staffing levels are more than adequate.
"We have not made any cut backs in staff across the last year or two," said Rosenthal. "In fact, we have more employees at UCLA than we did a year ago.
At UCLA Medical Center, a level 1 trauma center, 550 replacement workers and administrative staff will be filling in to cover the jobs of striking employees.
Officials said 25 percent of the elective surgeries scheduled at UCLA Tuesday and Wednesday have been postponed.
Rosenthal said patients may experience delays but the hospital will continue to ensure patient safety.
"The strike is in effect and the major impact is that there is some noise in the front of the hospital," said Rosenthal. "Inside the hospital, we're taking care of patients the way we always do."
The UC system tried to prevent 13,000 nursing assistants, operating room scrubs and other health care workers from going on strike, but a Sacramento judge denied that request Monday with the exception of respiratory therapists and some pharmacists.
The American Federation of State, County, and Municipal Employees is representing the workers. The union says the key issues are pension reform and staffing levels.
"That's our main concern because we've seen corner-cutting," said AFSCME President Kathryn Lybarger. "We've seen chronic understaffing and that's because the university is putting their hefty profit margins not where they belong with patients but into their own executives' pockets."
Rosenthal criticized the union's decision.
"Well we're very disappointed, as are the UC officials, that the union has elected to put patients potentially in the way of their own economic interests," said Rosenthal.
The union says that workers will leave the picket lines and return to work in the event of an emergency.
Health care workers from hospitals at UCLA, UC Irvine, UC San Diego, UC Davis, and UC San Francisco are participating in the strike.
The strike is scheduled to continue through Wednesday.