Objective: To compare the safety between conization alone and hysterectomy for patients with adenocarcinoma in situ (AIS) of the cervix. Design: A cohort study of AIS patients during 2007-2021. Setting: Women’s Hospital of Zhejiang University School of Medicine. Population: A total of 453 AIS patients diagnosed by conization who underwent cervical conizations only (n=153) or conization followed by hysterectomy(n=300). Methods: The clinicopathological and follow-up data were reviewed. Univariate analysis was examined by chi-square test and multivariate analysis was performed by logistic regression analysis. Main outcome measure: The rates of residual disease in specimens of hysterectomy and repeated conization were compared between positive and negative margin of conization. And the rates of recurrence were compared between patients treated by conization(s) alone and hysterectomy. The factors influencing residual disease and recurrence were assessed, respectively. Results: Among 310 specimens of hysterectomy or repeated conization, the rates of residual disease were 50.56% (45/89) for positive margin and 2.26% (5/221) for negative margin, with a significant difference (p=0.000). Totally 4 patients recurred as vaginal intraepithelial neoplasia（VAIN）in those treated by hysterectomy and 1 recurred as cervical squamous intraepithelial neoplasia (CIN) in those treated by conization(s) alone. The rates of recurrence were 0.65% (1/153) for conization(s) alone and 1.33 % (4/300) for hysterectomy, with no significant difference (p=0.431). Hysterectomy was a factor influencing neither residual disease nor recurrence. Conclusions: Conization is an effective and safe option for patients with AIS of the cervix, provided the margin is negative. Keywords: adenocarcinoma in situ, conization, hysterectomy, margins.