The stars, who play lovers in the new romantic thriller, stopped by the Children's Medical Center of Dallas in Texas on Tuesday (29Jan13) and posed for pictures with patients.
They also sat down for a special radio interview which was broadcast throughout the hospital, answering questions from youngsters receiving treatment there.
Hough and Duhamel continued their whistle-stop tour the following day (30Jan13) at the Children's Hospital of Philadelphia in Pennsylvania, where they met with sick kids and their families and signed autographs.
Hough took to her Twitter.com to share photos and videos from both events, writing, "Loved our visit to (the hospital) today! Everyone was so amazing!"