The R'n'B star, who was due to perform at Birmingham's NEC Arena last night (12.10.07) as part of her "Good Girl Gone Bad" world tour, was advised by doctors not to go ahead with the show.
The reason for the doctor's orders is yet to be confirmed.
A statement released by the Birmingham NEC read: "As per Rihanna's doctor's instructions, Rihanna will be unable to perform."
"Rihanna plans to reschedule this date as soon as possible."
"She appreciates the love and support of all her fans and wants nothing more than to see and connect with them. We apologize for any inconvenience."
The 19-year-old beauty had already missed a concert at Nottingham Arena on Saturday (12.08.07) and has also postponed her planned performance at Bournemouth International Center tonight (12.11.07).
A spokesman for the "Umbrella" singer was unavailable for comment.
Fans with tickets have been advised to keep them until further news is received.
Rihanna is scheduled to perform at Newcastle's Metro Radio Arena, the SECC in Glasgow, the Brighton Center and London's Wembley Arena later this month.
Her European tour began in Paris last month and is due to end in Moscow on December 21.
