Some of Vanderbilt’s youngest patients got a surprise visit from some special guests on Friday.

Country music legend Dolly Parton and Dr. Mehmet Oz visited Monroe Carell Jr. Children’s Hospital and met with children in the infusion center.

Parton led a sing-along and talked with patients and their parents. She released her first children’s album, “I Believe in You,” on Friday.

In a surprise announcement, Parton pledged to donate $1 million to the hospital in honor of her niece, who was treated there for leukemia several years ago.

“We are here in honor of my niece, Hannah Denison, and I pledged a million dollars because that will help go a long way for some care of the kids,” Parton said. “Because they were so wonderful with Hannah when she had leukemia here, it was the least I could do.”

Dr. Oz met with parents and shared advice for those looking for reassurance. He said he will be spending the weekend in Nashville.

Parton will be on Oz’s show on Monday.