Understanding the normal anatomy and size of the extrahepatic biliary tree is vital for surgeons to make informed decisions regarding the necessity of additional procedures beyond cholecystectomy. The extrahepatic bile duct (EHBD) comprises the common hepatic duct (CHD) and the common bile duct (CBD), with the former formed by the convergence of the right and left hepatic ducts and the latter extending from the CHD to the duodenum. A normal diameter is indicative of the absence of any signs of obstruction in the EHBD, and the determination of the average range for these ducts are essential for identifying pathologies that may require further surgical intervention. Cholecystolithiasis is a common condition managed at the Philippine General Hospital (PGH). Trans-abdominal ultrasonography is frequently utilized to diagnose cholecystolithiasis, and it can also be used to determine the size of the common bile duct. Knowledge of the normal CBD diameter aids clinicians in distinguishing obstructed bile ducts from normal ones, prompting further diagnostic tests for improved patient management. However, there is limited data on the average diameter of the CBD among Filipino patients with this condition. The study aimed to determine the mean diameter of the common bile duct and common hepatic duct among patients diagnosed with cholecystolithiasis with no signs of obstruction in the EHBD managed at the PGH.This prospective cross-sectional study included 80 patients who underwent cholecystectomy with intraoperative cholangiography. The CBD and CHD diameters were measured using intraoperative ultrasonography, and the data were analyzed using descriptive statistics and independent t-test.The mean diameter of the CBD was 5.17 mm, with a range of 2.7-10 mm (1.41) mm. The mean diameter of the CHD was 4.71 mm, with a range of 2.3- 10 mm (1.59) mm. There was no significant difference in the CBD and CHD diameters between male and female patients, and across different age groups.In patients with cholecystolithiasis managed at the PGH, the mean diameter of the CBD and the CHD was 5.17 mm and 4.71 mm, respectively, with no significant difference between genders and age groups. The mean diameter of the CBD among Filipino patients with cholecystolithiasis is similar to those reported in other countries. These findings may have clinical implications for the management of patients with cholecystolithiasis, particularly in the planning of endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic cholecystectomy. Further studies with larger sample sizes and different populations are recommended to validate these results. These findings can aid clinicians in determining the need for pre-operative Magnetic Resonance Cholangiopancreatography (MRCP) or selective intraoperative cholangiography to detect extrahepatic bile duct obstruction.