Purpose: To analyze the effects of cervical transformation zone (TZ) on the colposcopic diagnosis of cervical intraepithelial neoplasia (CIN). Materials and Methods: The authors retrospectively evaluated 482 patients who underwent conizaion between September 2012 and September 2016. The cytology, colposcopic impressions and histological diagnoses from biopsy and cone specimens were compared. Results: An agreement of 88.1% was observed between high-grade cytology and final histological diagnoses among the three TZ types. Significant differences between the colposcopic impressions and final histological diagnoses were observed for TZ types 1 and 2 vs. type 3. The overall agreement was 89.1% regarding the histology findings on colposcopically directed biopsy (CDB) and cone specimens, which correlated significantly with TZ (p = 0.004) and the number of cervical biopsies (p = 0.032). The agreement between histology results on endocervical curettage (ECC) and the final histology results was 28.24% in the patients with TZ type 3. Conclusions: Cervical TZ types variably influence colposcopically diagnostic accuracy for CIN, and TZ type 3 was associated with the lowest accuracy.