The clinicopathological significance of HER-1- and HER-2-overexpressions (OE) (HercepTest score 2+ or 3+) in biliary cancer and their relationship to the efficacy of adjuvant chemotherapy (ACT) were assessed. In 72 biliary cancer (28 gallbladder and 44 bile duct cancer), HER-1 and HER-2 were stained immunohistochemically in formalin-fixed, paraffin-embedded specimens. The ACT included uracil and tegafur (UFT)-based chemotherapies. Out of the 72 cancer, OE was observed in 31 specimens (43%) for HER-1 and 47 (65%) for HER-2. However, their OEs were not correlated with each other. HER-2-OE was inversely correlated with the clinical stage (p=0.0482). HER-1-OE was correlated with distant metastasis (p=0.0263), but not with the clinical stage. Neither the OE of HER-1 or HER-2, nor their co-expression, showed any significant effect in term of patient survival. In the HER-1-OE (-) patients, the survival rate of the ACT group was significantly higher than that of the surgery-alone (SA) group (p=0.0423), but in the HER-1-OE (+) patients, there was no statistical difference in survival rate between the ACT and the SA group. In contrast, HER-2-OE had no significant effect on the efficacy of ACT. Multivariate analysis also demonstrated that the histological grade and ACT were significant variables, but T, N, M and HER-1 and HER-2 were not significant variables. In conclusion, neither HER-1-OE or HER-2-OE were prognostic factors of the biliary cancer. However, HER-1-OE may be a useful marker for the indication of ACT.