The aim of this prospective study was to investigate the diagnostic accuracy of DNA-Image-Cytometry in addition to oral exfoliative cytology taken from suspicious oral lesions in our clinic. Cytological diagnoses obtained from 1500 exfoliative smears were compared with histological and/or clinical follow-ups of the respective patients. Additionally nuclear DNA contents were measured after Feulgen restaining using a TV image analysis system. DNA-aneuploidy was assumed if abnormal DNA-stemlines or cells with DNA-content greater 9c were observed. Sensitivity of our cytological diagnosis in addition to DNA-Image-Cytometry on oral smears for the detection of cancer cells was 98,3%, specificity 100%, positive predictive value 100% and negative predictive value 99,6%. The application of DNA-Image-Cytometry with DNA-aneuploidy as a marker for neoplastic transformation in oral smears secures cytologic diagnosis of cancer. Smears from brushings of all visible oral lesions are an easy practicable, cheap, non-invasive, painless and safe screening method for detection of oral precancerous lesions and squamous cell carcinoma in all stages. We conclude that DNA-Image-Cytometry is a very sensitive and highly specific, objective and reproducible adjuvant tool for identification of neoplastic cells in oral smears. Schlagwörter: cancer screening, cytology, oral cancer, dna-cytometry