Background/Aims: The early gastric cancer has been defined as that in which the depth of invasion is limited to the submucosa regardless of the lymph node(LN) metastasis. However, in the carcinoma of extrahepatic bile duct, the definition of early cancer may be different, because of the differences of histologic features such as lacking of muscularis mucosa and submucosal layer. Recently, Mizumoto et al. Proposed the definition of extrahepatic bile duct cancer, in which invasion limited to mucosa and fibromuscular layer, however there have been no data in Korea. The purpose of this study is to clarify the concept of early carcinoma of extrahepatic bile duct in Korea. Methods: We evaluated the 60 cases underwent radical operation due to extrahepatic bile duct carcinoma at Severance Hospital, Yonsei University from January l980 to December 1993. Results: The invasion limited to the mucosa(Tla) was noted in 2 cases(3.3%), fibromuscular layer(Tlb) in 11 cases(18.4%), adventitia of fibromuscular layer and serosa(T2) in 22 cases(36.77c) and invasion of adjacent organ(T3) in 25 cases(41.6%). The LN metastasis was found in 16 cases(26.7%). No LN metastasis was noted in Tl, however in T2 the LN metastasis was found in 27.3%(all Nl) and 40.0%(N1: 4 cases, N2: 6 cases) in T3. All cases of Tl but one who recurred at 16 months after surgery survived without recurrence. Disease-free survival according to the T stages were: in Tl, 100%, 90.9%, 90.9% at l, 3, and 5 year, respectively; in T2, 80%, 56% and 37%, respectively; in T3, 83%, 58%, 58%, respectively. The survival rate of Tl was significantly higher than that of T2 and T3(p=0.03). The mean survival in patients of T2 without LN metastasis was 50.5 months, which was longer than that of 38.7 months in cases of T2 with LN metastasis. Multivariate analysis revealed that the depth of invasion was the only significant prognostic factor. The polypoid type and papillary adenocarcinoma were frequently encountered in early cancer comparing advanced cancer. Conclusions: Early cancer of the extrahepatic bile duct could be defined as the tumor invaion restricted to the mucosa and fibromuscular layer. (Korean J Gastroenterol 1995;27:690 - 699)