To determine the effect of large-loop excision of the transformation zone (LLETZ) on the ability to interpret adequately the pathologic specimen and surgical margins.Fifty consecutive LLETZ specimens were used for repeat histopathologic assessment with emphasis on the interpretability of the surgical specimen and margin. All reevaluations were performed by a single pathologist. Complete lesion evaluability was defined as satisfactory accuracy of the histologic diagnosis and the ability to evaluate thoroughly all surgical margins. Medical records of the patients from whom the specimens were obtained were reviewed and analyzed for possible correlates to the status of specimen interpretability.Histologic accuracy was sufficient in 46 cases (92%). Extensive heat distortion precluded full assessment of the ectocervical margins in ten (20%) and the endocervical margins in 22 (44%) of the cases. There was no difference in complete lesion evaluability whether LLETZ was performed solely for treatment in cases suitable for ablative procedures or for both diagnosis and treatment in patients who traditionally would have undergone a cone biopsy. If the latter group (N = 25) was analyzed separately, extensive heat distortion made histopathologic diagnosis impossible in four cases (16%) and precluded full assessment of the ectocervical margin in eight (32%) and the endocervical margin in 12 (48%).The high rate of surgical-margin thermal destruction, with related limitation of interpretability, may represent a serious diagnostic and therapeutic limitation of the LLETZ procedure when considered as an alternative to cold knife conization.