This study was designed to determine the risk factors for abnormal Papanicolaou (Pap) smear after large loop excision of the transformation zone (LLETZ). We retrospectively reviewed the medical records of 343 women who underwent LLETZ between 2006 and 2008. The associations between clinicopathologic characteristics including margin status and abnormal follow-up cytology were analyzed. Forty-two (12.2%) women were found to have abnormal Pap after LLETZ. Old age at the time of procedure (21.2% versus 10.1%, P=0.020) and endocervical resection margin involvement (33.3% versus 10.7%, P=0.004) were the risk factors for abnormal Pap after LLETZ. The histologic grades of LLETZ pathology were inversely correlated with abnormal follow-up cytology (P=0.018). Logistic regression analysis revealed that old age, endocervical margin involvement, and lower histologic grades of LLETZ pathology were independent risk factors for recurrence. Our findings show that a positive endocervical margin is an important risk factor for abnormal Pap after LLETZ, suggesting that women with positive exocervical or deep cervical margins could be followed up with reassurance.