Objectives: In the 2019 WHO classification, intrahepatic cholangiocarcinoma (iCCA) was pathologically subclassified into two types, depending on whether it derives from small or large bile ducts. The iCCA located in the peripheral region of the liver have reported less invasion, less lymph node (LN) metastasis, and better prognosis compared to that of iCCA located in the proximal or central region (Orimo T. J Gastoloenterol., 2018; Lee W. Eur J Surg Oncol., 2020; Kosaka H, Asian Pac J Cancer Prev., 2021). However, these studies were conducted at a single institution, with a small number of cases, and lacking a fixed definition of “proximal” and “distal”; thus, reaching a consensus was difficult. In our current study, we will investigate the impact of the anatomical classification of iCCA based on the relationship between Glissonean pedicles from an oncological perspective. Methods: Patients with iCCA that underwent liver resection between 2011 and 2020 will be included. Data on patient characteristics, preoperative CT findings, surgical outcomes, and prognosis will be collected. Following examination of preoperative CT images, iCCA tumors that do not attach to either the main, second, or third branch of the Glissonean pedicle will be classified as “peripheral type”, and tumors in contact with any of them will be classified as “proximal type.” The primary endpoint is prognosis (overall survival and disease-free survival), and the secondary endpoints are surgical margin and LN metastasis. Possible effects: It may be possible to estimate the degree of tumor progression and prognosis based on the anatomical classification of the iCCA. Prospect for spillover effects: Anatomical classification of iCCA may impact the indications for adjuvant chemotherapy or selection of surgical procedures such as LN dissection in open/laparoscopic/robotic hepatectomy.