We designed this study to evaluate any factors associated with positive surgical margin in conisation specimens and to determine the optimal cone size. The medical records of patients who had undergone a loop electrosurgical excision procedure (LEEP), cold-knife conisation (CKC) and needle excision of the transformation zone (NETZ) procedure were reviewed retrospectively. Two hundred and sixty eight women fulfilled the inclusion criteria. Univariate analyses showed that 'postmenopause', 'HSIL on smear', 'previous colposcopic examination revealing HSIL in endocervical curettage (ECC) material and in two or more ectocervical quadrants' and 'managing with LEEP' were significant predictors of surgical margin positivity. Nulliparous patients showed significantly lower rate of surgical margin positivity. 'Postmenopause', 'previous colposcopic examination revealing HSIL in ECC material and in two or more ectocervical quadrants' and 'HSIL on smear' were identified as independent predictors of surgical margin positivity according to multivariate analyses.IMPACT STATEMENT