Abstract. Background/Aim: Previous studies on the accuracy of 5-aminolevulinic-acid-mediated photodynamic diagnosis (5-ALABiliary cancers, such as perihilar cholangiocarcinoma, gallbladder carcinoma and intrahepatic cholangiocarcinoma, are one of the most difficult cancers to manage regarding staging and radical resection. Despite these facts, preoperative diagnosis, management, and operative strategies have improved. Major hepatectomy and vascular reconstructions for curative resection of biliary cancers are highly invasive surgeries associated with high morbidity and mortality, with a 5-year survival rate of approximately 40% (1-6).Biliary carcinoma exhibits multiple recurrence patterns with distant metastasis such as liver or peritoneal metastases being most common. Therefore, many patients already have small, minimally-invasive, occult liver or peritoneal metastasis before undergoing surgery (1, 7). Presently, modalities such as computed tomography and magnetic resonance imaging are inadequate for the detection of small occult lesions. Improved detection of small lesions could inform surgeons to avoid any unnecessary surgeries.The metabolite of the amino acid 5-aminolevulinic acid (5-ALA), termed protoporphyrin IX (PpIX) selectively accumulates in tumors. PpIX emits red fluorescence peaking at 635 nm under blue-violet light excitation of 400-410 nm (8). In clinical trials, Stummer et al. (9) first demonstrated the use of photodynamic diagnosis (PDD) using 5-ALA to diagnose malignant glioma, intraoperatively. Subsequently, 5-ALA PDD 905