Objective: To identify clinicopathological factors that predict endocervical margin involvement of CIN2+ after cervical conization. Methods: 464 patients undergoing LEEP at Department of Obstetrics and Gynecology, Rajavithi Hospital, Thailand between January 2014 and June 2019 were analysed retrospectively. The patients were divided into two groups as a negative and positive endocervical margin of CIN2+. Clinical factors and the cyto-pathological characteristic were included. Univariate and multivariate analysis were used to identify the risk factors predicted positive endocervical margin. Results: 150 (32.3%, 150/464) women had endocervical margin involvement of CIN2+. Mean age in positive endocervical margin group was significant older than negative endocervical margin group (47.8 ± 12.9 versus 40.8 ± 11.5 years old, p <0.001). There are more significant post-menopausal women in positive endocervical margin group (p<0.001). In positive endocervical margin group, there were significant higher grade on cervical cytology, higher grade on histology of LEEP specimen, and glandular involvement of LEEP specimen. In univariate analysis, age of ≥ 50 years old, post-menopausal status, ≥ HSIL on cervical cytology, and glandular involvement of LEEP specimens were independent risk factors for predicting endocervical margin involvement. Moreover, in multivariate analysis, age of ≥ 50 years old and glandular involvement of LEEP specimen show significant difference between two groups. In endocervical margin involvement of CIN2+ group has 2.84 (95% CI: 1.23-6.56, p = 0.015) and 2.41 (95% CI: 1.58-3.66, p <0.01) times more age ≥ 50 years old and glandular involvement of LEEP specimen respectively. Conclusions: The age of ≥50 years old is the only pre-operative variable in this study. This finding is consistent with many previous studies. Therefore, performing LEEP in the women with the age of ≥50 years old should be aware the result of positive endocervical margin