Objective To evaluate the value of bile and serum CA19-9 in diagnosing biliary tract carcinoma. Methods Bile and serum CA199 and CEA were determined by radioimmunoassay (RIA). Results The dividing value of bile CA199 is 12 000 kU/L, and its sensitivity and specificity were 85.71%, 73.91% respectively. The dividing value of bile CEA is 480 μg/L, and its corresponding indexes were 57.14% and 77.17%. The false positive rate of bile CA19-9 and CEA were 26.09% and 22.83%. Serum CA19-9 sensitivity, specificity were 80.00% and 85.11%; the corresponding indexes of serum CEA were 68.57% and 82.97%. Conclusion CA19-9 is an effective tumor marker in diagnosing, deciding whether the tumor has been radically resected and in monitoring its response to the treatment.