First Lady Nancy Reagan and an entourage of life-sized cartoon characters, White House staff and Secret Service agents visited the brightly colored wards of Children's Hospital yesterday, leaving holiday gifts and a check for $25,000 for its young patients.

A banner that read "WELCOME MRS. REAGAN" stretched along the wall of Ward 4-yellow, as Reagan's party inched its way to a group of small children. They had been waiting for days to meet the president's wife, and were awed by the smiling woman dressed in green and red plaid when they did.

"I made this present for you," said 9-year-old Steve Washington as he gingerly handed Reagan his crayon-colored Christmas card.

Thank you very much," Reagan said, as she bent to accept it from the boy dressed in a hospital gown and connected to an intravenous machine.

"Thank you all very much," Reagan said, standing to walk to the next playroom of sick and injured youngsters. Similar scenes were repeated during the rest of her visit.

Yesterday's holiday visit was the third in three years that Reagan has made to Children's Hospital. The occasion was prompted by her concern for children, a White House official said. Hospital officials said the money will help purchase and operate its new heart-lung machine for newborns with severe respiratory problems.

The funds were donated by American Telephone and Telegraph, USF&G Insurance, the Ford Motor Company and the National Broadcasting Company, said Tom Sawyer of NBC.

In the check presentation ceremony in the hospital's atrium in the afternoon, Reagan also gave special gifts to three young patients.

One of the children, six-month-old Bradley Hill, received a Cabbage Patch Doll twice his size. When his mother, Janice Hill of Fredericksburg, reached out to accept her son's gift, Reagan reached out for little Bradley.

"I have to give him up now?" the First Lady asked, as she returned Bradley, the first baby helped by the heart-lung machine, to his beaming parents.

"I think you have my finger in there," Reagan whispered to 9-month-old Salinda Smith, whose tiny hand curled warmly around the First Lady's finger. With her voice almost slipping into baby talk she said, "I would love to stay."