There is a variety of mistake sources of histopathological workup of biopsies and resection specimen. Among those are the incorrect or missing transmission of clinical findings and data. The most critical opportunities for producing mistakes are the histopathological examination, diagnosis and classifications. Many of these mistakes bear the potential to induce a wrong therapy. Generally, the use of forms, check lists and standardized diagnosis sheets may help to reduce the mistake rates. Comparison of own data with quality indicators enables pathologists to validate their own findings.