A FLASH memory erasable by page includes a flash memory array containing a plurality of floating gate transistors arranged in pages, and a checking circuit for checking the threshold voltages of the floating gate transistors. Programmed transistors that have a threshold voltage less than a given threshold are reprogrammed. The checking circuit includes a non-volatile counter formed by at least one row of floating gate transistors, a reading circuit for reading the address of a page to be checked in the counter, and an incrementing circuit for incrementing the counter after a page has been checked.