Patients who have to spend their Christmas in the hospital, away from family members, are there for very serious health reasons.

At Sutter Medical Center in Sacramento, one doctor has an annual Christmas Day tradition, hoping to spread some holiday cheer.

"Ho ho ho! Merry Christmas!" Dr. Elias Kiwan exclaimed, as he entered the room of Jose Ruiz in the Blood and Marrow Transplant (BMT) Unit.

"Thank you so much, Dr. Kiwan," Ruiz said, as he received a hug and a goody bag from Kiwan, who was dressed like Santa.

"I'm Santa!" Kiwan corrected Ruiz, sparking laughs from Ruiz and his wife Ana.

Like the real Saint Nick, Dr. Kiwan is filled with the Christmas spirit and comes bearing gifts.

"I'm here to share their suffering, and this is what we do," Kiwan told ABC10 News. "We have to stay with them and make sure they are happy and safe."

For the past five Christmases, Kiwan has come in on his day off, dressed as Santa, to visit the patients who are too sick to go home and celebrate the holiday with their families.

"They get chemotherapy. They are very sick. They cannot go to home or they will most likely die," Kiwan explained. "So we keep them here, and in order to feel Christmas, we come with gift and a smile."

This is Lois Dyer's second Christmas here. Last year it was leukemia. She's in remission now but is back in the hospital with pneumonia.

She has met Dr. Kiwan's Kris Kringle twice now.

"I was so amazed that he was willing to take time out of his Christmas Day, from his family, for his patients," she said, wiping tears from her eyes.

Paul Sterling is assistant nurse manager on this unit.

"It's indescribable," Sterling said. "They cry. Dr. Kiwan cries, but he won't cry in their room. He'll cry sometimes outside of the room."

Most of the patients in the BMT unit have some form of cancer and are receiving chemotherapy.

"They have leukemias, lymphomas, myelomas, some solid-type tumors, and they can't go home. They'll die if they go home," Sterling said. "This time of year is really, really emotional. We have sometimes parents that can't go home and see their kids at Christmas."

Such is the case for Ruiz, who has leukemia.

He told ABC10 it's difficult "being away from family, especially my son."

He and his wife have a 2 1/2-year-old boy.

"Hopefully today we can go home and stay a little bit with him and celebrate Christmas," Mrs. Ruiz said, tearing up. "Even though things seem really harsh right now, we can still be grateful because we have the chance to fight and we have had amazing support from the hospital, the nurses, family members."

Patients on Monday said Santa's visit was a welcome gift of joy.

"He's an amazing doctor and an amazing human being and we love him deeply," Mrs. Ruiz said. "Nobody would've thought that we would've spent Christmas like this, right?...Hopefully next year, the Christmas that we celebrate will be different, a little merrier."