The foundation, with 10 million followers globally, has a strong presence in the South Bay. The 58 patients who showed up at Slonaker Elementary School on Sunday were matched in number by Tzu Chi's volunteers, including medical professionals and others. The group, which has a partnership with Slonaker and two other schools in the Alum Rock Union School District, chose the school because of its high poverty index.

The group, which also runs clinics in the Central Valley, targets the areas of greatest need.

But while the medical need in the neighborhood near Lake Cunningham is clearly high, a recent increase in immigration raids may have dampened the turnout, said Brenda Hernandez, a Slonaker teacher volunteering Sunday. After fliers about the clinic were distributed, several families said they were afraid that attending might draw attention from the authorities.

Those who did visit the clinic, which also included a fully equipped dental van, made good use of the services, Tzu Chi representative Eric Chen said.

Among them was Juan Martínez, who got a tooth capped, while his wife, Alejandra Leyva, also received care.

"It's pretty difficult to get an appointment at the hospital," said Martínez, of San Jose. Disabled last year in an auto crash, the uninsured man said the typical wait is three to five hours in emergency rooms and up to 12 hours for nonemergency care at Valley Medical Center.

At the Tzu Chi clinic, he said, paperwork was minimal, compared with the multiple applications required at most clinics and hospitals.

From a doctor's viewpoint, clinics present at least one challenge -- ongoing treatment of patients with chronic diseases like high blood pressure and diabetes. "When you write a prescription, you feel they should get follow-up care," said Richard Chiang, a cardiologist with Kaiser Permanente Hayward Medical Center, who has volunteered with Tzu Chi for about six years.

On Sunday Chiang mostly did consultations, emphasizing lifestyle. "I've been reinforcing the importance of people taking care of themselves with diet, watching their weight and getting regular physical activity," he said.

But while the doctors themselves couldn't follow up on their walk-through patients, they handed out information on community clinics for low-income residents and low-cost prescriptions available at drugstores. And the Health Trust of Santa Clara County distributed information about medical insurance available to children.

The accomplishment is hard to measure, but on Sunday, Tzu Chi -- which means "compassion and relief" -- made a bit of progress in its mission, Chen said, to help the most needy and less fortunate in society.