The price of a first class stamp rises by two pence to 32p from today.
The increase is part of the Royal Mail's attempt to work out future financing as it deals with competition since the postal market was opened up in January.
But the firm has been reined in from pricing its stamps too high by its regulator Postcomm, until 2010 when first class stamps will go up to 37p.
Today's price rise will also see first class franking prices go up to 31p, second class stamps up to 23p, and a second class franking price will be introduced at 22p.
The Special Delivery service will increase by 25p to #4.10 for mail up to 100g.