Selena Gomez has cancelled appearances at state fairs in Delaware and Ohio because of strained vocal chords.
The teen star, who stars in the Disney show Wizards Of Waverly Place, issued a statement saying she was disappointed she had to cancel the shows.
Selena also has the starring role in the film Ramona And Beezus, which is currently in cinemas in the US.
Delaware State Fair officials said the show could not be rescheduled before the end of the fair, and full refunds will be given to those who purchased their tickets directly from the Delaware State Fair.
The Ohio show was rescheduled for November.
Delaware fair officials said Allstar Weekend will perform in Selena's place for free.