Objective. The aim of this study was to ascertain whether cold knife conization alone for cervical adenocarcinoma in situ is safe. Methods. One hundred consecutive patients with a histologically proven adenocarcinoma in situ (AIS) of the cervix were studied from 1970 to 1992. Results. Ninety-two women presented with abnormal smears, and of these 56% contained abnormal glandular cells. Sixty-seven (74%) of 90 women who underwent colposcopy had an abnormal examination, but a glandular abnormality was suspected in only 19 (28%). In all, 80 cold knife conizations were performed. In 7, no abnormality was found following punch biopsy. The margins were free of disease in 55 (75%). The most commonly involved margin in the remainder was the apical. Conization was followed by hysterectomy in 20 women: in 8 of these the cone margins were free and residual disease was found in 2 of the extirpated uteri: as these were extramural cases, inadequate sampling could not be excluded. Of the 12 women where hysterectomy followed conization with diseased margins, 9 had residual disease in the hysterectomy specimen. The definitive therapy was cold knife conization in 56 patients, hysterectomy in 38, and electrocoagulation diathermy in 6. Follow-up of the 53 patients treated by conization alone ranging from 1 to 16 years, with a mean of 8 years (3 have been lost to follow-up) revealed no recurrence of AIS or adenocarcinoma to date. Conclusion. It is concluded that cold knife conization is a safe therapeutic modality, provided that the cone biopsy has been adequately sampled and the margins are free. (C) 2000 Academic Press.