About 29,000 University of California nurses, pharmacists and radiologists have joined a three-day strike to support service workers' demands for higher wages.
The medical workers joined the walkouts Tuesday, which led to the re-scheduling of thousands of surgeries and other medical appointments.
Dressed in bright green T-shirts, the medical workers are picketing outside 10 campuses and five medical centers along with 25,000 custodians, security guards and gardeners.
The strike was called last week by American Federation of State, County and Municipal Employees Local 3299 after the union and the university could not agree on a new contract.
University officials say service workers are already paid at or above market rates and that it cannot afford the nearly 20 percent pay raise over three years the unions is demanding.