A method and circuitry for checking the programming (P) and deletion (L) operations of memory cells (5) in a nonvolatile memory device (1). Parallel to the programming (P) or deletion (L) operations of the actual memory cells (5) the respective programming or deletion process is carried out on at least one similar checking cell (4.1, 4.2, 4.3), with the programming (P) or deletion (L) operations being less favorable by a defined extent than the programming (P) or deletion (L) operations of the actual memory cells (5). From the content of the checking cell (4.1, 4.2, 4.3) an evaluation device (6) determines whether the programming (P) or deletion (L) operation was successful or not, and a corresponding output signal (ak) indicative thereof is produced.