OBJECTIVE To investigate DNA image cytometry for predicting the prognosis of cervical intraepithelial neoplasia (CIN). STUDY DESIGN Smears from 151 women affected by CIN 1 or 2 on cytology with minimal follow-up of three years were included. Sixty-seven showed progression, with histologically confirmed carcinoma in situ or invasive cancer. Eighty-four cases showed regression of the disease, which was cytologically, histologically and colposcopically confirmed. Papanicolaou-stained smears were destained, and the Feulgen reaction was performed with consecutive image DNA cytometry of suspicious cells using an image analysis system (Cires, Zeiss, Germany). The DNA index of the greatest stemline and the number of single aneuploid cells, using 9c exceeding events, were computed. RESULTS In the group with progression, an aneuploid DNA stemline was found in 25 smears (26.9%). In 64 cases (66.7%) more than one aneuploid event was detected. The total number of aneuploid cases in this group was 76 (81%). In the group without progression, the number of aneuploid stemlines was 2 (2%). Single aneuploid cells could be found in five cases (5%). The overall number of aneuploid cases in that group was five. The sensitivity was 74.3%, positive predictive value 85.2% and negative predictive value 77%. CONCLUSION Aneuploidy is a marker for prospective malignancy in cervical Papanicolaou smears. DNA image cytometry, as an additional method, can be used to predict outcome in patients with CIN 1 and 2 of the cervix. DNA cytometry is not a screening method but can add further information for a treatment decision in doubtful cases.