The value of repeat cytology in the detection of high-grade: pre-invasive or invasive disease was analyzed at the time of colposcopy in cases of patients with abnormal referral cytology. A series of 136 patients with squamous abnormalities in their referral cytology, who had undergone repeat cytology and for whom outcome had been established, were included in the study. Final diagnosis consisted of 27 negative results (20%), 37 cases of CINI (27%), 31 CIN2 (23%), 39 CIN3 (29%), and 2 (1%) cases of squamous cell carcinoma (SCC). Referral and repeat cytology suggestive of atypical squamous cells cannot exclude high-grade squamous intraepithelial lesion (ASC-H), high-grade squamous intraepithelial lesion (HSIL) were findings significantly associated with a final diagnosis of CIN2 or worse. Sensitivity and positive predictive value of repeat cytology for the histological diagnosis of significant histological neoplasia (CIN2 or worse) there 81.9% and 77.6%, respectively. In women with referral cytology findings of atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion (ASC-US/LSIL), repeat cytology was suggestive of HSIL in 20% of cases (11/54), and in 4% (2154) biopsy was negative or CINI, and the final diagnosis established by LLETZ was CIN3. Eight cases (10%) of HSIL in referral and repeat cytology in which biopsies were negative or insufficient were diagnosed as CIN3 or worse in the final diagnosis. Repeat cytology would have changed therapeutic management in 4 and 10%, respectively, of patients included as ASC-US/LSIL and ASC-H/HSIL in referral cytology. Diagn. Cytopathol. 2009;37:68-73. (C) 2008 Wiley-Liss, Inc.3716873