To determine the effect of Chlamydia trachomatis (CT) on the occurrence of secondary bleeding following large loop excision of the transformation zone (LLETZ), 103 patients with cervical intraepithelial neoplasia (CIN) were included in this study. In order to determine the presence of CT infection, cytological material for direct immunofluorescence analysis was obtained prior to LLETZ. After surgery, the patients were followed up for postoperative bleeding. Groups with and without postoperative bleeding were compared as regards the frequency of CT infection. Of 103 patients, 8 (7.8%) were CT positive and 95 (92.2%) were CT negative. Postoperative bleeding only occurred in 6 (2.8%) patients, all of whom were CT negative. Thus, in CT-positive patients, no secondary bleeding occurred. CT infection of the uterine cervix in patients with CIN is rare and does not appear to be important for the occurrence of postoperative bleeding after LLETZ.